UV, quite true. Have you ever watched a mid-air collision on radar? Seeing two tracks approach, knowing neither aircraft is on frequency, seeing them merge, and then random returns as the wreckage falls?
The OP asked:
What would be the safest way to fly this route, in terms of the different ATSUs I should contact?
Best of luck.
(Off the top of my head, mid air collisions in the UK run at one every eighteen months or so and average slightly over two fatalities each, and are in busy-ish airspace outside CAS).
If I wasn't clear above, I'd be getting at least a Traffic service, and also flying defensively.