QUOTE(Rainbow @ Jul 18 2006, 10:53 PM)

Lol, I was talking to my dad and he was like 'See how you feel at the end of the week' and I said 'so I'll just have to phone them then because I don't want to go there after Friday' and now he's getting all stressy about notice.
If they have not given you a contract with your terms and conditions stating how much notice you are required to give then there is no legal requirement.
I would think for a casual a week should be reasonable (should you want to be reasonable of course)
In any case they have broken the law regarding working time, so I see no need for you to be reasonable. You might however want to use them for references so don't go cutting off your nose to spite your face. Think of the long term and how it might affect your future prospects.
What can they do if you just walk? Legally nothing.
Do they pay you in arrears? If they do it may be worth doing the week to get the money otherwise they may try and withhold it in lieu of notice not given.
EDIT
More thoughts.
Have a think about why you want to leave and then ask for an interview with your boss. Say you want to give a week's notice because you are unhappy working there because of ...then give your reasons (but nothing personal) such as:
*The hours are not what I was lead to believe when I took the job
*I find it difficult to fit in my other commitments around the working hours here
*etc
Then this gives them a chance to renegotiate before you finally throw in the towel.
Also when you apply for your next job and they ask you why you left this one you don't say "I couldn't stick it any longer so I walked out" you say "They misled me over terms and conditions and when I asked to work to my original terms they refused, so I gave notice and left".