In reply to marsbar:
Firstly, has a proper application definitely been made to add it to the definitive map? Check your local county council's website as they have an obligation to put these applications on an online register. They're called Schedule 14 Definitive Map applications if the register isn't easily found and you need to search the council's website for it.
If a proper Schedule 14 application has been made then there's nothing else you can do but wait until the council gets around to it which, as you say, could be a while.
In the meantime you have no right to continue using it and the council can't do anything about obstructions or private signs, because the right of way is, as yet, unproven.
If it's nowhere near the landowner's house and you can still walk it (you say it's been blocked for cars but you don't imply it's been totally blocked) then I'd just continue using it if I were you. If confronted, feign surprise, be polite and apologetic and turn back if asked. Remember that trespass isn't a criminal offence so the worst that can happen is that you get asked to turn back.
If confrontation with the landowner is likely and/or the track is totally blocked and you don't fancy continue using it then take solace in the fact that councils usually prioritise investigating Schedule 14 applications in such circumstances.