Find out who is responsible for the CCTV. (The publican? The brewery company? The council?).
Then write a letter to to the relevant person or body. (If you don't know a name, address the letter to 'The Data Controller (CCTV)". State that, under your rights defined by the Data Protection Act 1998, you require them to provide you with a copy of the recording within 40 days. Enclose a cheque, payable to the relevant person/body for �10. (The maximum fee that a data controller can charge is �10. In practice, it's the only fee which is ever charged). Give as much information as possible, so that the relevant recording can be readily identified.
It's your legal right to have a copy of any CCTV recording which shows you, so you must be provided with the evidence you require.
This leaflet has a standard form which you can copy/modify. (It's designed for accessing computer data but it's just as valid for CCTV).
http://www.ico.gov.uk/upload/documents/library /data_protection/practical_application/subject _access_-_guide_for_data_subjects.pdf
Alternatively, the form used by Hampshire County Council for CCTV is here:
http://www.hants.gov.uk/pdf/dataprotection/sub ject-access-cctv.pdf
(Once again you can modify it to meet your needs but you don't need any form. A letter will do just as well).
Chris