UK Landlord Forum / Life

I have found myself in a very difficult situation and all my own doing
I rent out a house to 4 occupants some of them friends who have lived there for several years
I never gave them a written tenancy agreement but generally they have paid the rent, however sometimes weeks late,  I don’t charge them too much rent
I need to sell the property and told them this 6 months ago naively thinking they would leave
They don’t want to leave and have sought legal advice and a couple of them have  stopped paying and told me I can’t evict them.
They also smoke cannabis which is overpowering .   I live next door
So my question is
It looks like serving them with a S8 is going to be very difficult  and I can’t serve them with a S21
Can I now give them a written tenancy agreement and wait out the 6 months then serve a S21
I know this is going to take time but I can wait if this is an easier path

I think you can serve S21.As I understand it,a tenancy does not have to be covered by a written signed document in order for a contract to be established between you.This also means you should have protected the deposit if you took one,and provided all the other certificates that are legally required.Others on here have more legal background and will help you.

Thank you so much for your speedy reply
I was getting really confused
And thought I could only serve a S8