Chez Bruce for uber posh foody grub. Snails and foie gras and a cheese board that goes for a run every morning. About £100 a head or more dependent on wine.
Brinkleys for a smart restaurant, English/French brasserie. £120 for two with a lot of house wine and really nice food. Deep friend cambert and steak and chips or liver and mash are faves
Bens Canteen for a more informal and cheaper and younger but still lovely night out, similar to Brinkleys for food
Harrisons: bit like Brinkleys and gorgeous food
Tooting has gone quite foodie in recent years. Tota is lovey and Chicken Shop is by the guy who owns Soho House. Haven't been to it though and it does have the best curries in UK
Northcote Road: avoid. It's full of restaurants that are over-rated except Rosita and the Sherry and their sister restautant Lola Roja
There is also a new Chinese dumpling place on the Pavement in Clapham, heard good things but never been.
If I was being taken out I'd want to do Brinkley's first then Rosita and the sherry
Hope this helps.
I am hungry now!