Hi Bet22,
For UK, you can’t go far wrong with Intercasino and 32red in my opinion. They’re both well-known brands in the UK and look after the players.
As for EU traffic, i think the europartner casinos do well, such as Casino Tropez and Europa Casino. Both have the site and the casino application translated into a bunch of european languages. Though im sure other people will have their fav’s…