Contract of employment for an apprentice

General information for the business: We are a plumbing and heating company
Legal topic: Employment
Description of legal work: We are taking on an apprentice aged 18 on week commencing 5th September 2016. He needs to be on PAYE and we are used to using subcontractors on a CIS self-employed basis. I therefore need assistance writing up a contract of employment for him.

We would like to include certain clauses such as continued work following the end of the apprenticeship (1 year) where possible. The reason for this is that if we are putting in the time and effort (and money!) to train him up, we would like to be reassured that he will continue with the company once he has completed it. We's also like to stipulate that if there is no work, we cannot pay him for those days where he is not working and would encourage him to use one of his holiday days if he wants to be paid on those days off. Furthermore, we would like for him to book his holidays when we book ours wherever possible.

Happy to discuss in more detail but I do need somebody who is legally trained please.
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