I love swimming and I love being outside. London is great if your into both these things. I swim at London Fields Lido which is heated all year round. Its best in the winter when the steam rises from the water and if your lucky its snowing a little on your head. If your brave you can also go for the unheated option of the Serpentine or Hampstead Ponds.
A traditional pie, mash and liquor shop in south west London that is run by the latest generation of the Harrington family who opened it in 1908. It looks like it hasn't changed since the day it first opened but it's a place with absolutely no pretentiousness to it at all, this is unapologetically working class and down to earth. If you want an overpriced cappuccino and wi-fi there's a Cafe Nerro down the road but if you want fantastic traditional London food you won't find anywhere better in the city. They even do pie and mash to take-away. I just wish it wasn't closed on Sundays.
The Almeida, in Islington, is a small theatre with big influence. It's an intimate place to discover groundbreaking theatre and get up close to some of Britain's leading actors. The cafe/bar across has a constantly-changing tasty menu, relaxed atmosphere and free wifi. Open all day and great place to spend time even if you're not going to catch a production.