How good is amazon.com in the UK?

Two of my grand kids will be moving to the UK in a few months. I am an amazon.com junkie and am always buying gifts and having them sent to family and friends across the US.
Does Amazon UK have as good a variety of items as the US? Does it have a Prime program for free shipping? I’ll be sad if its limited to just books.
Is there a better online retailer over there that I should be considering?