As far as I know, if the seller is Amazon themselves, you will have no issues, if it is not - god knows!do they collect also custom duty? Because when you import something, you must pay first custom duty's and then after adding the duty's percentage, sum the product price, to the duty's and then the shipping and then on that number, add the VAT.
So if they only collect the VAT, then some customs will stop the product to ask and extra payment for products that are required to pay custom duty's. For example, computer hardware is exempt from duty's but a pair of trousers would not for most of the countries. I don't know the situation in this case with the UK tbf
Sometimes, if you are in USA (or another country), Amazon may redirect you to US Amazon, with different prices.
You only know, if you try.