The law gives you freedom of choice to join a union or not, and to carry out union activities or use union services in your own time (or in work time where allowed). You are protected from being discriminated against on these grounds. This means that it would be unlawful to treat you less favourably on account of your union membership, or non membership in the following circumstances:
Dismissal relating to union membership, or non membership, is an automatically unfair dismissal for staff with 'employee' status, and other workers such as casual or agency workers can bring a claim for detriment if dismissed in this way. Both employees and other workers are protected from detriment related to union membership or activities.
