Tenancy Guarantor - can I escape?

[fastrack1966]

I read this thread from years ago but am still confused about this. Possibly I can escape from my guarantor status if the terms of the tenancy change, e.g. the rent rises. However the tenancy changed to a periodic one with all parties' agreement. Is that not a change to the terms of the tenancy? I.e. can I escape as being a guarantor?
Also I have seen a Safety Clause referred to in this context, but is that "Safety" for me or for the landlord/agent?

[islandgirl]

Did you see the AST before you signed the agreement? Why do you want to escape? Do you think the tenant is not going to pay?