UK Landlord Forum / Life

I regretable signed a tenancy agreement in Dec 12 with 3 other persons to share accomodation from July 13 for 12 months - in the meantime it has become impossible for me to live with these persons.  I informed them and the letting agency know that I wanted to terminate my contract and even found a replacement tenant (of whom the others declined) back in January 12 - does anyone know how I stand? do I have the right to refuse moving in and funding? etc - please help!