Is this an AST?
But you have only signed the initial tenancy rather than a renewal?
In that case you are only liable for that tenancy agreement.
Whatever the AST purports to do, the law will only render you liable for the period of the AST that you signed unless you sign a renewal.
That said, of course some tenants can do a lot of damage in quite a short space of time so you do need to be careful about the guarantees that you sign.
However, it is not an open ended arrangement and you can always sue the tenant if you have to pay under a guarantee.
Can I clarify anything for you?