Tenancy matter

[Habgood]

We rented our house out privately on a six month shorthold tenancy agreement. The tenant is our property (who was recommended by someone) has been the tenant from hell. She never told us that part of her rent would be paid by Benefits and the part that she should pay to make up the rent has not been paid for four months. We have served her with a section 21, and the date she is due to leave the property is next Monday 18th June. She refused to answer all our correspondence, so we do not know her plans. We have now been served with a Section 21 by our landlords as they are coming back from Egypt. Our plan is to move back into our property, but where do we stand if she decides to 'stay put'. Our old neighbours have advised us that she has neglected the property and the fools that we are we did not do an inventory. Your advise would be greatly appreciated.