Which type of tenancy do i create for these occupants.....?

Tenancy Types and Management

Hi. I have a 3 bedroom residential property. Some tenants (students) would like to rent the property and they seem sensible enough to make good tenants. The setup here is: 1 couple (for 1 bedroom), and 2 individuals for the other 2 bedrooms. I don't want to go down the route of a HMO. The main tenant has agreed to take on responsibility to ensure that the rent is paid for the duration of the contract (each month), regardless of the comings and goings of the other 2 tenants. Can i create just one contract for this type of scenario for all the tenants? Any alternatives?

On a side note, if all of them are students, do I as the landlord need to pay the council tax? Also, if one of them is in full time employment, does that mean that individual has to pay the entire council tax for the property?

Thanks