thanks for your reply, that was very useful.
We have an accountant, but he never pointed out how we could make any tax savings. I think the reason is that our potential tax savings are not great enough for tax advice to be beneficial, in other words there is not enough in it for him. How much does tax advice cost? 5K? 10K? I just had the scenario where I ask some advice re IHT, told me that IHT will be due (I know, that is why I asked for advise!) copy & pasted stuff that you can read up on the gov website, told me to see a financial adviser, and sent me a huge bill. I can't ask him anything.
Perhaps there is a blog about Capital Allowance and Research & Development which will help us make the right decision.