Since your endo was that useless, I'm wondering what was in the letter of referral your GP wrote. I'm very suspicious about whether or not he/she sabotaged you before you even got to see the endo. If that was the case there is little you could have done to have improved the appointment. You could phone up and ask the hospital for a copy of the letter. It might be interesting (or depressing).
I realise I could be doing your GP a disservice here, but I know such sabotage does go on.
You only have two options now, as far as I can tell :
1) Ask your GP for a referral to another endo for a second opinion. I think this has little chance of success since you had such a hard time getting the first appointment. But I am not sure what your rights are with regard to getting a second opinion - maybe someone else knows. Before you even broach this subject with your GP though, I suggest doing your homework on which endo you want to see, so you don't just get lumbered with another idiot.
2) You could self-medicate. I'm sure you know that many people do this.
I can't think of any other choices, sorry.