Depending on what sort of machine you are flying also consider using London Military out of CAS. You need to be at or above FL100 for their service but I have found them to be equal to airways controllers and they do look after you well.
Going west to East or visa versa there are a network of military corridors you can use depending on your altitude capability.
I am not sure what you are flying whether its a mild single or more complex and capable single/twin.
Out side of CAS it is usually again the good old military who give RAS and you do not need to file IFR only to fly IFR rules and levels.
As another poster stated even airways into smaller fields you are often dropped out and left on your own for the descent and landing
Pace