Visit in May with the Boys
Some Southwark places:
Vivat Bacchus (branch at London Bridge) - very good food (had a great dinner there recently). The wine list is heavy on South African bottles, the couple of SA reds that I've tried have been delicious and balanced; undoubtedly New World wines, but not fruit bombs, and come across as vivacious and spirited, but balanced. Bonus: a cheese room with very nicely conditioned cheese.
Another potential option is Table, more straightforward and solid cooking.
For something more laid back and casual, I'd consider getting lots of cured meats at Viva Verdi (the Culatello is intense). Loved the polenta special there too - perfect blanket of gorgonzola, synergising beautifully with sweet, fruit jam of some sort, and chickpeas cooked just right (firm, with a tiny nutty crunch).
Wentworth is near Virginia Water... my stepdaughter went to school in that area, and we've eaten nearby a few times. You'll be near Windsor, Bray (The Fat Duck), Eton etc. There were some places mentioned on this board in the past month or two... you could try a search for names. In Bray there is also a very good gastropub - The Hind's Head plus a few other offerings.