Hello Veronica
I think the waiting time at the moment is about eight weeks, depending on where you live and how much of a backlog they are dealing with. It must seem and awfully long time, when you're ill and in pain.
If you're very much concerned you could always contact the DWP and ask how long it is likely to be?
As for your GP, is there not someone else in the practise that you could approach for help - he doesn't sound very helpful - old age does NOT necessarily mean to have to live in pain, and it's his job to find you relief from it. Why not ask for referral to a pain clinic - they might have some answers for you.
When you get your response from the DWP and hear when you have to attend your face to face, p

lease get back to us and other members or mods will be able to let you know what is likely to happen, since it's your first application.