How should I deal with a tenancy agreement?

[tight fart]

I have a property I’d like to sell, the tenants have been there a number of years, I’ve explained
that I need to sell but alternative accommodation in the area is scarce.
They have offered to increase the rental to a more realistic market rent if they can stay for another year (about a 33% increase) I’ve excepted this and said that should they find somewhere else
they can leave without penalty or notice.
My question is what to do about a new tenancy agreement, leave it verbal or start a fresh one?
When they moved in it was by local estate agent on a finders fee only (they did the epc etc.)

[tight fart]

Thanks for all the above, yes I'm pretty well up-to-date with the regs etc, gas, deposit, ehic and so on, I'll check the last elec survey.
I had thought of selling with them in situ but at the rent they were paying it wasn't a great prospect.
I'm happy for them to stay another year at a fair rent so I'll see how it goes over the next year.

[tight fart]

Thanks for all the replies, if anything it shows how confusing the law is.

Superlightr you say you think private landlords should be regulated, my
impression is that they are, to the same standard as letting agents.