Dear Sir/Madam I have a tenant who I gave 2mths notice

Dear Sir/Madam
I have a tenant who I gave 2mths notice on the 1st Dec which was in line with the terms of the lease. On the 3rd Dec no rent was put in the bank for the month of Dec the rent been due on the 1st of every month, I text the tenant to ask the reason why and she stated that she does not have the money to pay for a credit check or the bond so her mother told her not to pay me my rent and use the rent money for the above and if I don't agree with this then they will not be able to move.
They also informed me that she had made enquiries regarding another rental and would I give them a ref and if they get the house the earliest they would be out of the house would be before Xmas and the latest would be New Year. To help them with the situation I agreed to defer the rent to pay these fees they were talking about and they pay me back at £200 a month to pay of the arrears which they agreed and signed for, during the conversation the husband asked if they were to move out by the end of month would they have to pay for the second months notice because they cant afford to pay both I informed them that they would not only up to whist they are living there
On the 4th Dec I received a call from the property Co asking for a ref which I gave.
On The 22nd Dec I texted the tenant for a update without a response, on the 27th Dec I rang the tenant again for a update knowing that they had been success in getting the new house again with no response.
Because I was getting no response I went round to the house on the 28th Dec and spoke to the husband he informed me that they had in fact got the house and he was suppose to be picking the keys up for the house the next day that been the 29th Dec but he was having to work so he did not know when it would be, so I asked him is he saying that they will still be the tenant in Jan and he stated no but it will be just a couple of days into Jan because they want to clean the house up, I stated this was fine and can the keep me informed.
They moved out of my house in fact on the Mon and they have been there ever since and my house is stood empty.
Today I went to where they are living now which is 5mins walk from my house and knocked on the door no one answered but I could see that someone was in, I then went to my house which is completely empty and locked up, I then noticed that the garage up and over door was slightly opened when I tried the lock the garage door opened fully with it full of rubbish and so was the side door of the garage open.
I then went back to see the tenant and again no one would answer the door so I drove away.
I then gets a text from the tenant asking if I had been to the house because her kids had informed her that I had been and if it was about the keys her husband informed me that they would bring me the keys on the 7th Jan and pay me a 1 weeks rent, which I feel is a little strange considering the rent is suppose to be paid on the 1st of every month and they had not paid for Dec rent as it is.
I text the tenant back and confirmed it was me that knocked on the door and that her husband said nothing to me about the 7th or the extra weeks rent only about signing for the keys on the Mon.
She then text me back stating that she had spoken again with her mother and she has told her that has she is still the tenant until the 31st Jan so she is keeping the keys until then and also that I am harassing her.
I like it noted from the 3rd of Dec 2014 until today I have had no contact or communication with the tenant until today I have spoke to her husband once on Sun the 27th Dec.
Please can you clarify to me please with the information that I have given have I the right to access my property before the 31st of Jan now they have moved out.
I know I will not get any of the monies they owe me without taking them to small claims court. I am selling the house and under the terms of the contract if I wish for professionals to visit the house which I do with prior notice they have to allow this they are fusing to give me my keys until the 31st like I have already stated
Thank you for taking the time to read my letter.
Rita Purdue