Payroll advice/set up

General information for the business: I want to start employing part time staff in my retail store
Industry: Business
Kind of support: Employee Relations
Description of support work: I have taken on two part time staff for my corner shop, the hourly wage for one is £7 ph, he is doing 8 hours per week, also has another job, second staff is doing 25 hours p/w at £6.50 p/h.
I need advice and contracts for a zero hour week, so I do not have to offer holiday pay/sick pay. The hours may be reduced at a later date, so this is why i do not want to commit to certain hours.
I need someone to advice me on how to work out TAX/ N/I also I need to supply the staff with wage slips, where do I get these from?

I need to have system in place so that I can pass on details to my accountant at the end of the month.
Extra notes: This is the first time I am employing someone.

Can I Offer employment on a self employed basis??

Do i need to notify any authority?