As for the DNA go to a solicitor and get a 30 min free meeting and explain everything that happened and say you are there to get legal advice on having you DNA removed from the data base he will be able to tell you if he think it is possible and he will also give you some forms to fill out for legal aid.
He may suggest other options open to you and possibly other legal points that you may wish to take up.
It should not cost anything.
The recovery of the cctv footage wont cost you.
As for the DNA go to a solicitor and get a 30 min free meeting and explain everything that happened and say you are there to get legal advice on having you DNA removed from the data base he will be able to tell you if he think it is possible and he will also give you some forms to fill out for legal aid.
He may suggest other options open to you and possibly other legal points that you may wish to take up.