I received a grant of £150 from McMillan towards high protection SPF clothing, it was through the McMillan nurse at the melanoma clinic I attend. She helped me fill out the application form - the grant is means tested though.
Ive bought from Sun-Togs and found their clothing to be very good (but bit pricey).
My late husband Kenny had quite a few shirts from Craghoppers with a high SPF, also some combat style trousers. Im not sure if any other outdoor suppliers may have SPF clothing, Paramo may be worth looking at and possibly Berghaus. I think they may be a bit cheaper than buying from a retailer who only supplies SPF clothing, or at least that is what we found a few years ago.
We buy alot of ours in TXMaxx if you have one. Its a bit hit and miss but sometimes we pick up some expensive clothes at really low prices. I tried John Lewis and they have SPF clothing for cyclists (vests would you believe-what is the point) but not golfers.
But yeh, TKMaxx often have Craghoppers.
Nike too.