.... does anyone have any advice or insight on registering for our wedding in the UK so my american family/friends can purchase online and ship to our place in the UK? .....
It depends exactly how much you family and friends are likely to spend on gifts but here are several thoughts.
Many things are much cheaper in the US - roughly as many $$$ as £££, so buying in the US is like getting a 40% discount.
If you bring a gift worth more than a certain amount (I'm not sure but it may be as little as about £120
) into the UK you'll have to pay taxes and duty. There is no special concession for wedding gifts.
Anything electrical should be bought new in the UK, otherwise you'll have transformers to deal with, which really is more trouble than it's worth when you could buy new in the UK.
Beds and bedding in the US is a different size, so unless you are importing an American bed you'll need British sheets for a British bed.
Try these stores to see if they do on-line wedding registries:
Debenhams,
John Lewis, and
House of Fraser, they are all chain department stores that have branches around the UK.
If you tell us where you'll be living then I'm sure that there'll be somebody here who can tell you which stores have branches in that town.