I regret to say that the landlord is under no legal duty to offer you a new tenancy, it is his decision who he contracts with unfortunately because ASTs do not grant tenants significant security of tenure. Hence why almost all residential landlord grant under ASTs.
If he requires you to leave at the end of the term then he must serve a s21 Housing Act 1988 notice upon you giving you two months written notice. If he does not do so, or serves an invalid notice, then you are not required to leave until a valid notice has been served and the notice period expired. If he serves one you can check it against one of the templates available from online document providers.
If a valid s21 notice has expired and you remain in occupation then he will only be able to evict you with a Court order, so he would have to apply for one once the notice period expires. He would, though, be able to sue you for the extra rent for the period and his costs in making the application.
I'm very sorry it could not be better news, but your only way of moving forward is attempt to reason with them in the hope they will see the logic of sticking with a responsible tenant rather than contracting with another unknown person.
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