Hi Room, I'm in the UK. I wasn't too bad physically when I quit (by which I mean no DTs), so I didn't need a rehab centre. But these guys helped me get on a SMART course and offered lots more support too. They probably know the best way to get you into a rehab.
http://www.turning-point.co.uk
Also, if you're completely honest with your GP, I'm sure they'll do their best to help. If you've already done that, sometimes I find it best to see a different GP. Some care more than others.
Or, as somebody else suggested, turn up to A&E to get help with your withdrawals. The NHS (because they're under so much strain) tends to wait until you're really suffering before it helps, and there probably is a space or two at a rehab nearby
Or call 111. They've got a lot of resources and info. AA too is an excellent thing.
Sorry you're suffering. But you can get free.