Work other company on days off

Employers can control who else you wish to work for, they hold your P45, they pay into your pension, NI etc…and they are responsible for the hours you work…which is why many will not like it if you want to moonlight, at the end of a period your card will be down loaded, and then the ■■■■ will hit the fan…some drivers are in my eyes unbelievable…we had one here a while back asking if he can work his holidays for someone else, after getting his holiday pay…and the company refusing to allow him to work for them during this period…he opted to work for an agency…seems to me the government did it all wrong by giving employees the right to a 4 week holiday per year…when all they want to do is work it…must be in a ■■■■ load of debt to want to do that.