hi,
might be too late, but I have some recommendations for future...
I like those restaurants, as I am Japanese...
Zuma: no doubt. it is the great place, same as roka. zuma does valet parking service. great for saturday lunch or sunday lunch as well as evening. surprising, but there are kids friendly. If you need a table, best to make reservations.
Roka: there is two branch, one in Charlotte street and other is canary wharf. Canary wharf does sunday brunch which is amazing. there is kids' play space inside the restaurant, only on sunday.
Umu: traditional and very elegant & classy
Yashin in high street ken: great but don't go there with starving stomach. When I went there with my husband and other couple. we did 2.5 round of whole menu and bill was quite something... Fantastic sushi, best to go when you are "medium" hungry
Chisou: three in london. one in beauchamp place, chiswick and off regent st. Casual and great great food.
Flesh and buns: this is more casual, relaxed and fun place to go. this is newly opened but always really really busy. the food is great. a lot of finger licking delicious food. (
http://www.fleshandbuns.com/) try the marshmarrow desert!!