I've had similar experiences of being 'dumped' by ATC - East Midlands once abandoned me at FL50 in IMC but importantly, that was after they had facilitated my transit IFR through their zone, not before. It's not helpful (and the air went a bit blue at the time, though in my defence I would say that I was solo) but I understand that my transit wasn't exactly their primary responsibility.
A Plan B is important but it's also important to think about your exit strategy at all stages - what if I can't get a clearance here after getting one here, &c.