AST rent increase and property inspection

Tenancy Types and Management

I have 3 questions. 

We have a tenant who's tenancy is coming to an end. We want to put up the rent to match another flat in the same block that we own. I've drawn up a form 4 which is "landlords notice proposing a new rent under an assured shorthold tenancy of premises situated in england" is this enough to send them to notify of the rent increase?

Also once we have notified them, can they continue a rolling contract at the new rent and just change the amount they pay to the higher amount or do we need to start a new assured shorthold tenancy agreement?

My other question is, we have been rented a flat to a couple for 12 months and we want to do an inspection of the property as we haven't really heard from them. How do you go about doing an inspection and what do we need to do please?