Although it depends on your experience, I went for an all girls flat in Allen Court in first year and am still best friends with the girls I lived with - we are even going to live together again for our 3rd year!! I don't think there's necessarily one set type of girls who go for all-girls, however in our case we weren't necessarily the kind to go out and drink every night of the week. That doesn't mean we never did however, and it doesn't stop you from socialising with all kinds of people. Some people claim it's usually international girls who pick this type but we only had one international girl and she's amazing. Another girl was 22 and engaged which I think might have been why she chose all-girls. The age range was 18-22 in our flat. But generally I think if it'll make you more comfortable then go for it! There's nothing wrong with mixed either, just depends on what you feel comfortable with.