Whats the legal most hours you can work if you are 16?

Im 16 and have just got a job in primark.
Im contracted for 8 hours for thursday evening/saturday/sunday

On my first day I worked 4 hours..then 10 hours on friday then 9 hours on saturday and 7 hours on sunday..10 hours on monday..3 hours today.

Today I looked at the rota and it says im working on monday for 4 hours and wednesday for 10 hours..saturday for 10 hours and sunday for 7 hours...but I havnt even been asked.

My questions are
1. How many hours is actually legal for a 16 year old? During Summer holidays? and during school days?
2. Do they have to ask me if I can work on a day that im not actually contracted for?
3. This is my first ever job and I've only been working there for exactly one week - are they allowed to just chuck me in the deep end like this and make me work 10 hour shifts.

thanks..

In the summer? Maybe... what state do you live in? There's probably a site for state labor laws as they do vary from state to state. And listen, once school is in and it's interfering with your schoolwork, then say something... RIght now, you're in the deep end, so SWIM... Imma tell you this now, MONEY makes the world go round. It controls everything, if you have money you have control... Work as hard as you can! Get that money while you can, and save it, seriously... and if you really want to know those answers, either post back with your state, or goto google.com and search for your states labor laws.

fairly certain the max they can work a 16 yr old is 8 hours a day with a max of 40 hours every pay period of two weeks... I believe... and anything after 8 hours is overtime anyways.

byaaa

I live in the UK