UK Landlord Forum / Life

My tenant is 2 and a half months into a year contract.  The contract does have an option to terminate at the 6 month point with 1 months notice.  My tenant has complained about noisy neighbours and still wants to move out after I have spent over £1,000 on a soundproofing solution which has been successful, I feel she simply has decided its not the right area for her after re-locating from London to Manchester.  She has advised she wants to move out and has found a new property and can I release her from the contract early.  She wants to move out on the 14th December and only pay the 3 weeks from her next rent due date of 24 November up to 14th December.  I have stated that the earliest break opportunity is at the 6 month point and she is liable for full rent up to that point however if I can find a suitable replacement tenant before then I will release her from the contract early and that she would need to cover any costs of re-marketing the property.  Can legally hold her to paying full rent up to the end of the 6 month point if I don't find a new tenant in the next few weeks?  I have also considered putting the property up for sale now, I am not sure I want to continue being a landlord, does it matter if I am planning to re-market the property for sale and letting and see what uptake I get?  Any advice greatfully received.  Thanks