Further info re 12 weeks
After 12 weeks of action, you have the right to claim unfair dismissal if:- your employer hasn't taken reasonable steps to settle the dispute; or
- you stopped taking part in the industrial action during the 12 week period and are dismissed for taking part during that period
If the action is official but unsupported by a ballot or unprotected (for example, because the action is secondary) you can only claim unfair dismissal if you are dismissed and others taking part are not.
so I could interpret that as it' okay to take part in industrial action up to
just short of 12 weeks, if you do not take part in action post that and are dismissed, it is deemed to be unfair. Again open to legal interpretation but that (source directgov) sates that if after 12 weeks the employer hasn't taken reasonable steps to settle the dispute, implying negotiations after industrial action have started. Either way I'm sure all the appropriate information will be sent with the ballot forms.
The only other reference I can find on workers rights which says it differently is
In some cases, it will be automatically unfair to dismiss an employee who continues to take industrial action after the end of the eight-week period where the employer has failed to take reasonable steps to resolve the dispute.
Again one for the legal eagles to chew over, seeing as Unite organise so many I'm sure they are aware of it and will make us aware of it, and so long as everyone has the facts to hand when they get the ballot form.
These are just my personal interpretations on the interpretation of the rules and I am not qualified to offer legal advice on such issues but I'm sure the CAB are, I will ask them tomorrow