Nice idea but your recording would not be admissable in court because there are very strict guidlines about recordings, the storage of the tape, date / time stamping etc. How would you go about proving that the voice on the tape is the voice of the person you state you have recorded?
The best solution is to have a witness with you and directly after the meeting both write up a statement - independently, signed by yourselves. If it is that important you can pay a solicitor to listen to you swear pn oath in his office. You then have an exhibit that could be brought to court.
Recording people is a tricky situation and requires specialist equipment to get a clear, uninterupted recording.