You could connect GLA-LGW-MCO but as stated above no direct BA or OW flight. Your best bet is going to be snagging the seats at T-355 at midnight.

Only thing I wanted to add was that if you have an Amex look at booking your Universal hotel with the Amex travel service. A couple of years ago I used our £200 Amex Platinum credit and a very healthy discount apparently not available anywhere else to pay for 4 nights at the Loews Royal Pacific and we had VIP/front of line passes with early entry for all of the Universal days and rode Hagrid's Motorbike Adventure and the Jurassic Park Velocicoaster every single day in the morning with minimal wait time- it was fantastic!