Updated 17 April 2026 — Microsoft's 15 April Copilot Chat restriction has now been live for two days, Microsoft 365 Copilot Premium lets you choose OpenAI or Claude Opus 4.6 per task, Copilot Studio's multi-agent orchestration and Agent-to-Agent (A2A) protocol have both gone generally available, and Power Platform's April 2026 feature update ships new AI capabilities inside Power Apps and Power Automate. The off-the-shelf box has grown, so the "when do I need custom?" question deserves a refreshed answer.
It's one of the most common questions we're asked: "Should we just roll out Copilot (or Gemini in Workspace), or do we need something custom?" It's a reasonable question, and the answer is almost always "both, but for different things." Understanding which tool belongs where will save you significant money and avoid the frustration of deploying an expensive AI product that doesn't deliver on its promise.
The major vendors — Microsoft (Copilot in M365), Google (Gemini in Workspace, formerly Duet AI), and a few others — have each launched productivity AI assistants. These are AI tools woven through existing office suites. They use your organisation's data as context, apply large language models, and help you draft documents, summarise meetings, generate presentations, and query data in natural language.
Pricing typically ranges from £15–30 per user per month (Microsoft 365 Copilot Premium is currently around £24.70 per user per month in the UK; Google Workspace Gemini sits in a similar band). As of April 2026, Microsoft 365 Copilot Premium also lets you choose between OpenAI and Anthropic's Claude Opus 4.6 as the underlying model — on a per-task basis, not as a tenant-wide switch. The line between "choosing a model" and "choosing a platform" is now much blurrier than it was twelve months ago, and that matters when you're comparing it against a custom build.
From 15 April 2026, Microsoft restricted Copilot Chat inside Word, Excel, PowerPoint and OneNote for users on the free Copilot Chat tier. Full in-app Copilot now requires a paid Microsoft 365 Copilot (Premium) licence. If your AI strategy was "everyone gets Copilot Chat for free and we'll figure it out from there," that strategy stopped working this week. It's a useful forcing function: are you actually getting value from Copilot, or were you just hoping you would? If it's the latter, targeted custom tooling almost always looks better than scaling Premium to the whole team.
Less talked about, but strategically bigger, is what happened inside Copilot Studio this month. Microsoft took multi-agent orchestration to General Availability alongside the open Agent-to-Agent (A2A) protocol, integration with Microsoft Fabric and the Microsoft 365 Agents SDK, and a meaningful expansion of governance controls, prompt authoring and model choice. Power Platform's April 2026 feature update layers on top, putting more AI capability directly into Power Apps and Power Automate flows.
In practical terms, the off-the-shelf box is now larger than it was at the start of the year. Workflows that used to require a custom build can increasingly be composed inside Copilot Studio — especially if your data lives in Microsoft Graph, Dataverse or Fabric. That doesn't make custom obsolete; it shifts the line. The new question to ask is "can Copilot Studio + an agent do this well enough?" before you ask "do we need to build something ourselves?"
For knowledge workers doing varied desk-based work, a well-deployed productivity AI can genuinely save 30–60 minutes a day — if they actually use it. Industry research suggests only around 11% of UK SMEs use technology extensively for automation, so the gap between "deployed" and "used" remains the real story.
It can't integrate with systems outside its ecosystem. If your business runs on a CRM, an ERP, a bespoke database, or any system that isn't part of the platform, the AI can't see it, can't read from it, and can't write to it — unless you build a connector, at which point you're doing custom work anyway.
You can't control its behaviour with the precision custom gives you. Even with Copilot Studio's expanded governance controls, you still can't match the level of enforcement you get in a purpose-built tool. Choosing Claude Opus 4.6 over GPT (or vice versa) inside Copilot Premium changes the tone and reasoning quality of outputs — but it doesn't change what Copilot can do, which is still bounded by the Graph and the apps it sits inside.
The outputs aren't auditable in the way compliance requires. For regulated industries, these tools' general-purpose nature makes auditability difficult — even with the new multi-agent audit logging, which is enterprise-grade rather than industry-specific.
It won't automate end-to-end processes at scale. Copilot Studio agents help individuals and small teams work faster. They don't replace a workflow that needs to run reliably, on a schedule, against your CRM or finance system, for the next three years.
For most of 2025, this piece lived as a binary — Copilot on one side, custom builds on the other. In April 2026 that's no longer accurate. A third category has emerged, sitting between the two: agentic AI products like Microsoft Copilot Cowork (General Availability: 1 May 2026, built on Anthropic's Claude agentic stack) and Anthropic's standalone Claude Cowork.
These aren't productivity suites, and they aren't bespoke builds. They're configurable agents that execute multi-step tasks across your tools with human checkpoints. They're more capable than traditional Copilot, more flexible than a custom single-purpose tool, and typically cheaper than commissioning one. For SMEs deciding what to do next, they now belong in the conversation alongside "subscribe to Copilot" and "build something custom" — particularly for cross-app coordination work that used to be custom-only.
The honest framing: off-the-shelf suits individual productivity, agentic AI suits delegating multi-step work within your existing stack, and custom still wins when the process is specific, high-volume, regulated, or requires deep integration with systems outside Microsoft or Anthropic's reach.
| Scenario | Off-the-shelf | Custom AI |
|---|---|---|
| Summarise a meeting | ✓ Off-the-shelf — native integration | Overkill |
| Process 200 invoices/month | Cannot do this end-to-end | ✓ Custom — built once, runs automatically |
| Draft a client proposal | ✓ Off-the-shelf — good for general drafting | Possible, but unnecessary |
| Answer customer queries from your knowledge base | Possible, but inconsistent | ✓ Custom — reliable, on-brand, auditable |
| Analyse CRM sales data | Can't access external systems | ✓ Custom — scheduled automated analysis |
| Onboard new employees | Partial — documents only | ✓ Custom — structured, consistent, connected |
| Prep for a client meeting | ✓ Off-the-shelf — Copilot "Prepare" surfaces prior context | Unnecessary unless CRM integration needed |
| Coordinate a new deal across Outlook, Teams, SharePoint, Excel | Agentic (Copilot Cowork / Claude Cowork) — ✓ from 1 May 2026 | Custom only when deep CRM/ERP integration is required |
For most UK SMEs, the optimal AI strategy combines all three. Roll out productivity AI to knowledge workers who will benefit from general productivity gains — and now that the free Copilot Chat tier has been narrowed, you'll need to decide which users genuinely warrant a paid M365 Copilot Premium licence rather than enabling everyone by default. Layer agentic tools (Copilot Cowork from 1 May, or Claude Cowork today) on top for the cross-app workflows that used to need custom glue code. Then identify your two or three highest-value, most repetitive specific processes and build custom AI tools for those.
The question we ask every client: "What does your team do every week that takes significant time, follows a consistent pattern, and produces a predictable output?" Those are your custom AI opportunities. Everything else is probably off-the-shelf — or, increasingly in 2026, agentic — territory.
If you're weighing up whether a productivity AI subscription is worth it for your business, whether a Copilot Cowork pilot makes sense at GA, or wondering what a custom tool for a specific process might cost and deliver, that's exactly the kind of conversation we have on a discovery call — and the AI Growth Lab gives you a way to try one custom automation against a real process before committing to anything bigger.
Book a 60-minute conversation — no sales pitch, just a clear assessment of where productivity AI makes sense and which processes could be custom-built.
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