London restaurants

[Gattabianca]

We are taking our 3yo for a few days in London, the first time he's been.
We are going to rainforest cafe one night - I know it's a lot of money for not very good food, but 3yo will love it.
So I'd like to balance that with some really good food for our other meals but I've not eaten out with kids in London since I was a child myself.
Any suggestions for family friendly-ish (don't need a kids menu, he'll eat pretty much anything) restaurants in Greenwich, South Kensington and Fitzrovia/kings cross? ideally somewhere London specific, not a chain we could eat in in Manchester.

Grain Store in Kings X. There's an Honest Burger as well.
Hawksmoor or Goodmanham for steak in Fitzrovia, Salt Yard or Barrafina for tapas.

Not sure it comes under the really good food banner, but Chinatown is always fun and interesting with lots to see and experience.

Goodmanham Goodmans

Canteen works well for mine. Don't know if there's a branch where you're looking. I use Baker st one

Lots of suggestions already - thanks!! I'll have a look at all of these.
I hadn't thought about Chinatown but that would be fun and we all love dim sum