I have to agree with Basil and say go for the type/role that most interests you. Starting your RAF career with half an eye on a commercial TR ignores the fact that you might be on a completely different aircraft type as you approach an option point or even in a ground role. In addition the requirements in the commercial world change so rapidly that what might seem like a sound decision now soon becomes completely irrelevant. So take this opportunity to pick an area/role/location/potential RAF career path you really want to do. Good luck.