Young people abroad--what do you do for housing?

I am a 23-year-old female American getting ready to move to the UK next week. I’m trying to figure out what to do for housing. I am looking at some ads for roommates wanted, but not everyone likes live accordion music :) I could also just wait till I get there and look for an ad from a little old lady looking for a tenant.

If anyone has done a similar thing, what have you done for housing?

Thanks!