Crying don't panic sweetie.
I run my own business dealing with landlords and tenant issues so can probably help you out!
Firstly have you explained to the landlord that you are pregnant and this is why you don't want the room? They get a lot of cock and bull stories so are a bit suspicous sometimes when someone can't take the room.
Secondly the tenancy agreement you signed should be on a joint and several liablilty which means that although each of you are renting a seperate room you are all laible for the others debt. So it is very difficult for a landlord to enforce the cost of 1 room against 1 tenant if it goes to court. Also the fact that the room may remain empty is not your problem its the landlords and a court would usually view that as part and parcel of owning and letting out property, especially in the student sector.
I presume that you aren't working at the moment and won't be for a good while once the baby comes along and will probaly return to uni. Whether you are planning on getting work or completing your course is irrelevant it's the fact that you have £0 income at this moment in time and for the forseeable future. It's only worth someone taking someone to court if they have something they can either sieze to sell AND they are confident on winning.
When did the Tenancy agreement stay it would start and when did you advise them you wouldn't need the room? If you have given a reasonable amount of notice before it should start it's the letting agent or landlord's job to fill the room in time for new term starting. Ask the agent what they have done to do this and ask to see copies of adverts etc.
Write to the landlord and the letting agent with an income and expenditure , a list of assets you may have, a copy of the letter or telephone conversation you had giving notice and state that you have taken legal advice on this matter and will not be paying any rent for the property nor will you be 'buying' yourself out of the contract. As a gesture of good will you will maybe pay £50 towards advertising the room again to try and secure a tenant. Or if you paid a deposit offer that as a one off good will payment.
If you want me to scan through any paperwork for you my work email is [email protected] I'm the only one who will see that so don't worry about anyone else opening it. Put it to my attention (Jodie) and I'll have a squint for you. x