Can somebody please help me before I go off the deep end at my boss?
I work in a local business. I've been there since September last year. I have no written contract. The first I knew of being on a zero hours contract was when I requested some proof of income for the WTC department and the boss (company owner) handed me a letter for them stating, "Shoddy is on a zero hours contract... ".
My job is consistently carried out on two regular days a week - from 10am until 5.30pm on Tuesdays and from 9am until 5.30pm on Wednesdays (16 hours in total).
I now know that this is not the definition of "zero hours" but until now it's not been an issue.
I am given payslips. I don't pay tax yet as I have yet to earn enough.
I'm NI contribution exempt (I have a small HMRC registered additional income from part time self employed work). My £0 NI contributions and the £0 tax are noted on the payslips provided by my employer.
I recently asked the boss about my holiday entitlement and was told abruptly, "You're on a zero hours contract. You don't get any!". Then he walked off. Nice! 
I said in that case I'd take the days off unpaid. This was agreed to. I return to work this forthcoming Tuesday.
I've been doing some reading up over the break and as far as I can make out I am entitled to paid holiday, pro-rata to the full time rate.
Is that correct please?
If it is, how do I approach the boss? In writing? In person? Invariably we're both busy and dealing with customers. He's not approachable, he is temperamental and I'm not tolerant of rudeness. This isn't going to end well.
Then there's the question of sick pay. Am I entitled to that?
Finally, there's the issue of the so-called "zero hours contract". As I understand it he doesn't have to offer me work but I don't have to accept any that's offered either. So going by the letter of the law could I say, for example, "Can I have next Wednesday off please? No, I can't? Oh well, I have no contract to work for you on that or any other specific day and I'm entitled to turn the work down so I'm taking next Wednesday off anyway!"?
I don't plan on doing this but I'm interested to know the answer, if only as some form of comfort for the injustice of the rest of it!
Thanks for reading this essay!