If you are there on Sunday make your way to the flower market at Columbia road, lots of little shops nearby, try to go to Angela Flowers if open,. Go early the market closes at 1.00 sharp.
if you are in Canary Wharf then you can visit Mallow, at wood wharf, an amazing vegetarian restaurant with the most delicious food, you won’t miss meat at all. If you have to have meat there is a Hawksmoor opposite.
museum of London (Docklands) nearby too.
lots of shops within Canary Wharf, mix of high street , chain, and high end.
west end shopping , Bond Street is fun for a gawp in the windows, Liberty because it is beautiful and they have just opened a new perfume room, Fortnums perfume department is good too, and if you go up Piccadilly towards the ritz you will find the little gem that is Santa Maria novella.
I like Marylebone high street for indie (posh) shops, spitalfields great for one off quirky, Camden passage I find exhausting, but kids love it.
if you go to Trafalgar Square then there is a great little gelato parlour on the road going down to embankment tube, they make the icecream look like flowers and it is delicious.
how old are your kids? Google Transport for London and find out how to get them reduced price travel cards, you and your dp can use credit cards, but remember to tap in and out to get the best deal. You will need one each.
a river boat trip is fun, just get the normal one not a tourist one, from embankment pier ( don’t forget the gelato! ), the trip down to Greenwich and back is good, you will see loads and Greenwich is a good place to visit anyway.
have a lovely time, most of usLondoners are friendly and happy to help, unless you block the escalators when we might bite, but London is also unfortunately home to thieves and pickpockets, so like in any tourist city, keep bags in front of you, across your body, make sure zips are closed, and be wary in cafes if you put bags or shopping down.