As an American who has stayed in the UK and other places in Europe, I have to say that getting laid even in western Europe is far easier unless you happen to be in the Mediterranean (Spain, Italy, and Greece). I have found that European women tend to have a more lax attitude towards sex. A lot of this relates to the fact that America was settled originally by Puritans and that level of sex shaming still exists throughout American culture, it's particularly bad in southern states but it is bad throughout the east coast. You have to finesse things more in the US.
I have got to say about British women, they are not as bad as everyone has said they are. While there are definitely ugly ones, I found them to be less into the radically left feminism BS than American, Canadian, and Aussie women were. It seems like English women were so tired of being shat on that they somehow decided to pick up their game. I have found them more pleasant abroad than say Spanish and Italian women (hands down the worst attitudes and the most mediocre looks in all of Europe).
British women are really slutty, far more slutty than American women. I met one who lived across the street from a nightclub, she was telling me to come with her to her place and we did it then and there.
An American guy can absolutely slay in Europe, as much as Europeans will deny it. Only exception is the Mediterranean which is heavily social circle based. European women adore American culture and they all have some degree of an inferiority complex to us, Europeans in general do no matter how much they talk up being cultured.