There is a minimum right to paid holiday, but your employer may offer more than this. The main things you should know about holiday rights are that:
you are entitled to a minimum of 5.6 weeks paid annual leave (28 days for someone working five days a week)
part-time workers are entitled to the same level of holiday pro rata (so 5.6 times your usual working week, eg 22.4 days for someone working four days a week)
you start building up holiday as soon as you start work ,eg 5.6 weeks divided by 12 months = 2.33 days a month for the first year then 2nd year you are entitled the whole amount from the start of the year ,but if they leave you work out 5.6 divided by 12 then if they have had more than the amount they owe you
your employer can control when you take your holiday
you get paid your normal pay for your holiday
when you finish a job, you get paid for any holiday you have not taken
bank and public holidays can be included in your minimum entitlement
So if your worker works 3.2 weeks work in 4 weeks that works out at 28 days / 52 weeks =0.538462
12 months /4 weeks =13 so times that with the 3.2 weeks work you do in 4 weeks =41.6 days times 0.538462=22.4 days holiday a year and by the way a verble contract stands as good as a written one ,so if the verble one stated that the worker only works 3.2 weeks out of 4 weeks thats what he gets paid for and you should be able to put this in a written contract.
The only way he can get pay for the days he dont work is if he worked eg a 40 hour week and then you dont have work for him ,he can claim for the days he dont have work .But if stated in a contract that from time to time work will be short he can not claim hope this helps