Record the meeting for your record if nothing else. I wouldn't bother asking for permission.
If it gets to an Employment Tribunal and they have done something wrong (eg procedure not followed, said something that they later deny, etc) that you can demonstrate with the recording, the ET *will* consider it, even though you didn't declare that the meeting was being recorded at the time.
If it gets to an Employment Tribunal and they have done something wrong (eg procedure not followed, said something that they later deny, etc) that you can demonstrate with the recording, the ET *will* consider it, even though you didn't declare that the meeting was being recorded at the time.