My foreman has got himself into financial difficulty and has taken on a second job outside and it is effecting his performance At my company. What are my rights ?

A letter needs to be drafted and given to him. The letter has to provide a very clear outline of what the expectations are of him and also indicate the problems you have had with him recently. It should also provide a warning that future performance issues may result in a dismissal. Ultimately, if the issues continue, you may be in a position to terminate his employment for cause. I would be happy to help you with the drafting of the letter.
Lior Samfiru