Good luck!
If you like walking try and walk around the centre as much as possible (without using phone mapping ideally), you'll realise it's quite small really and get to know the place. Take some time to experience the history, art galleries, theatre etc I wish I'd done more of that now I live in the provinces.
Take time to see different parts of the UK, although I loved living in London for 2 years and visit a lot I way prefer other parts of the UK and now a lot of people live remotely it's practical to live in the midlands for example and go there for work once a week maybe.
Take regular trips to Europe by plane, train or car. It's cheap and doable for a weekend. There is a lot of variety between countries/cities which I think you'd really appreciate.
'you'll realise it's quite small really and get to know the place.'
I've been here for ~10 years and feel like I'm familiar with a fairly narrow slice of it (mostly north/north east a little bit). A good mental model imo is to see it as a collection of smaller towns, each with distinct urban centres, that have grown into each other. This makes it endlessly interesting to me and I feel like I'm unlocking new parts of it all the time.