UK Landlord Forum / Life

Myself as a group of 4 other students have signed a tenancy agreement to rent a property beginning this September. We have paid the deposit and had assumed it was all sorted until we moved in. A member of our group has just said that she plans to leave the group and replace herself with another tenant, for which she will find. If she fails to find a new housemate to take her position, she will continue to pay the rent that she would have had to pay anyway. Our agency has told us that If she fails to find anyone to take her position in the house within the next two weeks that it will jeopardise the agreement that the rest of us has, and they will kick the remaining four of us out of the agreement. I was just wondering what the legal standpoint on this was, as it seems to me that if the agency get their money, they should have no issue with it.