Yes, legally they are only allowed to keep you in temporary accomodation for six weeks if you have a family (which you do if you're pregnant)... but that doesn't always count for much I'm afraid

We were in our B&B room for almost 3 months in the end! Their answer whenever we said that they were oblidged to house us was "yes, but we can't house you if we haven't got anywhere you can go. We can't find anywhere accessible, so we can't house you." It should hopefully be a lot quicker for you because you don't need a ground floor accessible property so you're a lot easier to house and the council won't have any excuses for keeping you in temp accomodation.
Best of luck, and yes please do keep me updated on how it's all going.
[Edit: If it gets close to 6 weeks and you've still heard nothing, get a soliciter on your case. Pop down and make an appointment with the Citizen's Advice Bereuax and enquire about legal help. If you are on a low income you will be entitled to free 'legal aid', which means that a solicitor can inform you about the council's legal obligations and informally fight your case for you. If you're on income support you will be entitled to 'legal help' which is where they will cover all costs should you need to go to court. In probability that won't be the case, though - most council's get a move on after an informal letter from a solicitor. It's definately worth having someone on side either way just to make sure your concil doesn't try anything...!]