Anything that is purchased and shipped in over the value limit (about £28 I think which includes chipping cost) is liable for VAT and import. Doesn't matter if it is marked gift or intended as a gift.
Personally carried items which have been purchased have the value limit as described above. Doesn't matter if it was a gift or intended as a gift.
Incorrect. It's £18 and this figure applies to internet purchases [or via telephone etc] whereby items are received in the post.
When you're bringing stuff in yourself [off holiday etc] then it's £390 [used to be £340 until recently].
Regarding B&H it's an interesting place to look round but I didn't have the time to go through the purchase procedure. You have to queue to order the item. Then you have to queue to pay for it. Then you have to queue to collect it. And they're not short queues either.