As others have said, I would return the letter to TESCO loans, and write on envelope the date he moved out, no forwarding address supplied, and the contact details of his solicitors.
For the telephone calls from creditors, have an answerphone message saying he moved out on ...and the telephone number of his solicitors for contact.
I personally had a heap of hassle years ago when someone (I didn't know) was fraudulently using my address for benefits, car licensing and mobile phone billing. At first I left it, thinking it was not my problem, but then I had to deal with bailiffs and the police turning up at odd hours. Now I would nip it in the bud as soon as possible.
I would do everything I could so that he was no longer linked financially to your address, and make sure if is off the electoral register for your address as well. Also his handyman company, have you taken your name off that and told HMRC or whoever etc.
If you think you will still keep getting loads of post for arse-wipe, print out some labels with "return to sender" and the solicitor's details, to make your life easier.
I know it seems like a lot of work, but will make things easier for you in the long-run!! If it also means its not so easy for him to get credit, or run up his legal bill...well tough cheese! 