Just an update on a question I asked before leaving for Orlando on 11th August. We went to Gatwick the day before as we only live 10 minutes away. Got there just before twilight check in opened and we were able to get the very front economy seats, row 21 with the extra leg room. We had to pay £30 each but we thought it was well worth it. I think there were only 4 rows of economy seats and we did definitely notice the extra room. We also got off the plane first so no queue for immigration. Will definitely try that again.