No permanent recruitment into LHR yet. As the IFS manager said recently, the next recruitment into LHR will most likely be on a temporary basis, and after the period expires it could be transformed into a permanent LGW contract.
Commuting from scotland is fine, I know many people who do it even in EF, however it might take a while to get the trips you want (longer ones or scottish night stops for shorthaul) so that could make it a bit more difficult; for longhaul it is less of a problem. Keep in mind though that you are not elegible for staff travel for the first 6 months or indeed while on a temp contract, so it might be cheaper to find an accomodation near the airport for that period.
Whatever you decide....good luck!!