agreeing a new AST with the tenant

Tenancy Types and Management

hi,
i let out a property in july to a very nice tenant, through a letting agent for an initial 6 month period, now its coming to the end of the 6 months i have decided to leave the agent as the service has been very poor, i have written and given them 2 months notice to terminate our agreement,

after speaking to the tenant we have agreed to start a new AST, where he will pay me directly, and to have a guarnator sign it also, but what else do i need to do as everything was done 6 months ago,

gas inspection certificate
inventory
credit checks

the tenant wants to stay for a long time, 5-10 years, so i have promised to keep the rent the same for the next 12 months, then we will review the situation.

i have also asked the agent to handover all the paperwork relating to the work they did when he moved in, should i also make a few checks myself?