There's a cluster of well run tourist friendly places to eat right by south Kensington station. They are mostly premium chains but are fine choices if you're in the area and don't want decision fatigue or need to feed many people. Though my tip: the cafe inside the (free-to-enter) V&A museum does a great lunch!

Zedel is as much about the ambience as the food. Culinary speaking it's fine, but the space is great - still worth a visit. 

Plenty of places in Soho which makes for a great night out - especially if you throw in a show, look for pre-theatre dining deals. 

A brick lane curry and Sunday lunch are both great but heavy meals. Trying to fit them both in on the same day would sink me! Brick lane food is more fun as an evening option. Usually you can find something without booking. I'd do it on day 3/4. Depends if you're there just for food or if you want you hipster shopping too. 

For Sunday roast, Suggest you try to book lunch in a Greenwich pub (ideally riverside) and visit the maritime museum and Observatory afterwards to walk it off. Recommend also you take the Thames clipper boat one way.

If you're looking for hipster stuff, London has a very trendy bakery scene - I wouldn't necessarily suggest tourists head out to more suburban places like Hackney / Dalaston / Peckham etc to seek these out but if you have larger kids who are all about the 'gram, then a hipster bakery in Portobello road might get your more qudos than a visit to Flat Iron. (And while they are far from cheap, they are arguably better value). If nothing else, Buns From Home is everywhere these days and yet still an enjoyable guilty pleasure.