Some useful information on recording phone conversations:
From
http://www.callcorder.com/phone-recording-law-uk.htm
"The relevant law, RIPA, does not prohibit individuals from recording their own communications provided that the recording is for their own use. Recording or monitoring are only prohibited where some of the contents of the communication - which can be a phone conversation or an e-mail - are made available to a third party, i.e. someone who was neither the caller or sender nor the intended recipient of the original communication.
According to Oftel, you do not have to let people know that you intend to record their telephone conversations, provided you are not intending to make the contents of the communication available to a third party. If you are you will need the consent of the person you are recording."
This is more or less the same over all the sources I've just googled for.
However
http://www.yourrights.org.uk/your-ri...ecording.shtml says:
"the combination of an evolving doctrine of breach of confidence and the possibility of a separate tort of privacy developed by the courts in the light of the incorporation of Article 8 into UK law, may well mean that a person can be stopped from revealing what was said and recorded in such a situation if it was apparent that the conversation was confidential and there is no public interest in such disclosure or the invasion of the person's privacy is otherwise unjustified."
This appears to allow you to use the conversation if it involved a matter of legal dispute, eg someone says something on the phone which they later deny, you could then AIUI (but I'm not a lawyer) use the recorded conversation as evidence of what they said.