Talk to H.M. Customs & Excise (not the 'Revenue, VAT is an excise duty not a tax). They will tell you. I suspect you cannot, due to catch 22: without CPL you cannot sell your flying skills. Until you are in the business you cannot claim. As far as I could work out you can only claim if you are improving your business opportunities, not establishing them.
Ask anyhow, it can't hurt!
Could you post on here if you have any luck, it would help a lot of the people here. I didn't even think of it at your stage!