Hardly anyone will take any notice of what I advise, but FWIW:

I am probably too old fashioned, but I think that somebody as little
experienced as the OP should learn to walk in something of
medium performance before running in a champion-class glider. I
am confident that many (most?) UK Chief Flying Instructors would
not let such an early pilot fly an advanced glider so soon. Ymmv.

Re what is the best glider, all such choices are compromises of one
sort or another. For most people, who are not going to be world or
national champions, a Lak 17b with FES in a Lak trailer, with one-
person rigging aids, is (I believe) substantially cheaper than an -27
etc., and would be good enough to give -27s, -29s and V2s etc. a
run for their money in equally skilled hands. In addition, it would
save needing a retrieve crew on most if not all occasions, enable
cross-country flights on days one otherwise wouldn’t, and give
more flying in less total hours per day devoted to it. And that would
greatly benefit a tyro pilot trying to gain experience to emulate the
top exponents, cheaper and faster than almost any other way.

IMHO.

Chris N