Your current MOT is still valid up until the expiry date shown on the certificate, you paid for a 12 month mot and thats what you have, this very topic was brought up on here a while back and at that time we had a visit from VOSA at my work and i asked the dude about this and was told the certifiacte is valid up until the expiry date regardless of whether or not it has been presented for another test early and failed.