It all depends on the individual controller.
The shall we say older sounding controllers don't in general do it or give a heads up. And speaking to mates the controllers who are also pilots tend to do what they would want.
Even on the same unit the way individuals deal with the same situation is different so unless you know the voice you won't have clue what to expect.
Personally I now expect no service and if I get one its a bonus. I try and stay in or above cloud sub FL100.
It still gets pretty hairy getting dumped out of London control by decent going into say CAM on a fair wx day. Some just dump you and others keep you until your VMC.
Even getting a service the two airprox I have filed have been under the old RAS service and under a deconfliction. One with a microlight and the other a glider. So although nice to have once your VMC below cloud base I prefer to have all eyes available looking out the window than head in running on vectors.
you doesn't pay your money and you doesn't get a choice.
And they are the ones that phone you and start bitching that you should have spoken to them so that you were known traffic. And they had needed to speak so they could get 5 miles deconfliction on a CAT aircraft which you could see anway and would be deemed seperated from in CAS but under ASTOCAS you would be vectored away from.
If you don't get a useful service why bother speaking to a unit?