I am flying from one and returning to another this summer. Was horrified to discover that the train from the Midlands would have cost £600 for three adults - obviously I should have booked sooner, but it's February! So I am driving so will need to get a coach from Heathrow to Gatwick when we return. Does anyone know if I need to book in advance? With the Flixbus there doesn't seem to be an option to have an open ticket but there seem to be hundreds? Will this cost me a fortune does anyone know?