Places in the UK to source an AP 15300?

[W44NEG]

I've previously owned a Royal Oak diver but it was quite a large, heavy watch for me as I'm around 3 stone wet through

So I'm interested in a 15300. I don't mind used and I'm expecting this is the way to go as it's unlikely I'll find one new now from a store.

Where are the "go to" places for AP for people on here?

Thanks