Guarantor and the small claims court

Tenancy Deposits

I have evicted my tenant via S21 and she vacated the property 1 April after a court order. I have in writing a letter I sent before hand to her, confirming she would have to sign papers, the deposit release form, check inventory, hand me the keys and the locks would be changed at 4.30pm.
However, on the aloted day she had moved out and was not present at the agreed time . I had a verbal OK from the Housing benifit office to change the locks which I did. I phoned my tenant to see where she was,and she said she had thrown away the keys. She asked me to dispose of all her belongings in the house as she did not want them.
Since then I have spent over £4000 putting the house back together again and had planned to sue the guarantor, for damage and the fact the tenant broke every tenancy agreement ever invented.
My one hesitation, is the fact that I did not get the bailiff and wait another 2 weeks to make the eviction abolutly water tight.
1. Have I made myself vunerable to the guarantors solicitor spotting this?
2. or have I safe guarded myself by writing the letter which she ignored.
3. The interested party/deposit lender, signed the deposit release form and is satisfied.
Dare I go ahead and sue?
4. Is his last known address legal to use even if he has gone? His abandoned wife is still there and says he has gone off with another woman.
5 Am I wasting my time? Shall I forget it?
6 Shall I hunt him to the death?
Advice please.