How easy (and expensive) is it to get from LGW to Luton airport?
http://coach.nationalexpress.com/nxbooking/journey-list
take the bus that goes direct at £26.00
Take the Thameslink train (Brighton to Bedford 3 times an hour) which stops at both Gatwick station inside the airport and Luton Airport Parkway station. From £16.80.
If you buy a ticket to Luton Airport Parkway you need to buy a cheap ticket on the short connecting bus into Luton Airport. Buy a ticket to Luton Airport from Gatwick and it includes the bus.
Don't buy a ticket to Luton. That takes you past Luton Airport Parkway into the town centre of Luton.
The train is much easier than the coach. Just check for engineering work on the line if travelling at the weekend.