Can I take legal action against my lettings agent?

I moved in to a house about a week ago, when I signed the contract it said the house was in a clean condition and the inventory only noted one or two minor issues, e.g. indentations on the stair carpets where previous tenant had a stairlift. However I moved into to find the house completely filthy, mould in some places which was omitted during the viewing and inventory. The house was dirty during the viewing but I told the estate agent it needed cleaning prior to moving in, when I signed the paperwork as it mentioned the property was in a clean state I thought it had been done. I've complained to the agent who has finally said, after trying to shirk any responsibility, that the landlord will release me from the tenancy provided that I continue to pay rent for up to 12months until new tenants are found and my deposit will be withheld until so. Can I take legal action as I feel that I signed the contract under false pretences as I would not have signed had I known the state the property was still in and the lettings agent took money under false pretences, also I wonder how hard the agent is going to try and find new tenants when I have to pay the rent for up to a year or until new people move in. Any advice please?