I work for a payday loan company in the uk. They make me work 1/2 hour before my shift without pay?

I am pretty sure this is not legal. If you have contracted hours and get paid hourly then all hours of work should be paid for. The only situation I have heard of extra hours for no extra money is when employees are salaried. This would probably be stated in a part of the contract which would say something about extra hours of work may be required. Hope this helps.