I believe that the statuary holiday pat (according to gov . Co) is 5.6 weeks. That bit I'm ok with, the bit I'm unsure about is the zero hours contract (which incidentally I've not signed)
It matters not whether you have signed the contract. If you have worked the job under those terms you have accepted them.
Yes you are correct about 5.6 weeks, sorry. But remember that does include bank holidays, christmas day, easter etc. if you look again at the Gov website and click onto the next page it explains how the holiday pay is calculated for casual workers. Ie zero contracted people. The same number if weeks as the rest of us paid at an average of the previous 12 week period.