DFC
Doing work for BALPA (or any other organisation) in work time where such activities were not agreed with the employer would be a breach of contract.
Google the following:
Hansard employment law
Read the UK Employment Acts 1996 & 2002, and try to understand the permissible nature of undertaking union activities, organising the workforce etc.
I assume by your tone, you have never picked up a newspaper, discussed your forthcoming holiday or even asked your colleagues how their day is going.
What a boring fellow.