What version of iTunes are you running?
I deliberately haven't taken the last couple of updates after reading about problems with the 'Match' thing that they've now started including.
As people above have said Brighton is busy all year round - and in the summer months many places won't take bookings of just one night. Have you tried making bookings of Fri / Sat or Sat / Sun nights rather than just Saturday only?
Bear in mind how close we are to London as well, so we get an...