Agreement Before Marriage Can I Get Out Of A Tenancy Agreement Before It Starts If I Find An Adequate Replacement?

Can I get out of a tenancy agreement before it starts if I find an adequate replacement? - agreement before marriage

I signed an agreement on a contract for 12 months from June 2010. I am a joint tenant with another 5th The circumstances have changed and I must go. I've put a replacement in the 5 housemates are happy. I made the transaction, or is it just for the contract and the owner? Can I use my security deposit? Thank you.