No, I don't think that you can request to live with a specific ethnicity as that, in a way, provides a leeway for (therefore promotes) racial segregation.
Give it a shot - if you seriously don't feel comfortable, you can always request to transfer to another accom but there's no guarantee that it'll be any better.
You don't have to be mates with your flatmates, and please don't feel pressured to drink or go out when you don't feel comfortable.
Cook what you like - if they're intolerant or make racist remarks, report it!