My experience is that much of the time, anyone with a radar service close to you will give you a basic service and when they feel you are too far away will suggest who to freecall.
Some just get too busy. I remember Gloucester went through a phase of refusing service (very nicely) and that’s fair enough if they have urgent local issues.
The thing to remember is that it doesn’t hurt to ask - if they cannot help they are generally polite and if they are not - well, you have not lost anything by asking.
London always seem happy to offer service and its always interesting to listen to them (I have to make sure I concentrate on my flying rather than trying to picture the traffic they are dealing with over the large area that is covered)
But remember - it’s your choice - call them or don't - if you feel more comfortable calling them do so - if you want peace and quiet for a while don’t. I am sure the anti's (on both sides) will converge on the thread soon - don’t let them try to tell you that "all the world is wrong except them".