Joint Tenancy

You may want to share the responsibilities of your tenancy with someone who lives with you as your wife or civil partner. 

Where the tenants are not either married or have a civil partnership joint tenancy will only be granted where the proposed new joint tenant has lived at the property for not less that one year and is a person who would be entitled to succeed to the tenancy in the event of the tenant's death. 

The existing tenant will be required to terminate his/her tenancy and a new tenancy will be granted.  You should apply to your landlord for a joint tenancy.