If the paint is thick enough it will block a good amount of the UV's but would need to see it. Also looks like it is in a hangar (most fabric aircraft are kept that way) so UV damage should not be a major issue. Do not get me wrong though, sanding back a fabric aircraft is a MONUMENTAL job that at the end of the day is nearly worthless compared to re-doing the wing. Alternatively you could just wait until all the paint flaked off, I would only think you would have to wait a month or so!!!!
If you change your mind Ian, I have a friend looking for a hour builder, does not really care for condition as he intends to fly the hours he needs and put it back on the market at a super low cost, so if your not interested pass on the details and I will let him know.