Been monitoring flights to Orlando for some while now. Today have booked with Thomas Cook from Gatwick to Orlando International on 15h April - 29th (did not look at other dates as this was the date I was after)
6kg hand luggage 7 1x23kg (can't split weight to more than 1 bag)
Cheapest before today was with 3rd party agents. Lowest price was £460-£480. Not all 3rd party sites are bad but make sure details input correctly as mistakes very expensive to correct.