Teaching contract - hours change

[Downtome]

Employed as an unqualified teacher for 30 hrs per week exclusive of breaks.
I don't actually get to leave the room for breaks/lunch ( half an hour each) as I need to supervise the students. I get given £2.30 as a meal allowance (staff used to get free meals for eating with the students).

Students were expected to be in by 8.30 for 9am start and finish at 2.30 pm. So I opened up at 8am to let in the early ones and finished at 2.30 ( obviously stayed longer if I needed). Which I worked out at 32 hours a week covering my hours and any statutory break requirement.
Now I have to stay until 3pm and they want to remove all staff from eating with students, so no £2.30. So effectively 35 hours a week and £11.50 a week worse off.

My contractual hours are from my previous role and state 8.30 3.05 and finish at 12.30 on Friday! No lunch money mentioned as it wasn't needed.
Can anyone help with where I stand and what I can suggest to the Head please.

I also got a 20 min breaks in the last role everyday away from the students.

Firstly, you are required by law to be given a break of reasonable length if you work over 5 hours. This cannot be whilst supervising students!
You need it in writing what hours you are expected to work, what breaks you will get, and what your job description is.

Firstly, you are required by law to be given a break of reasonable length if you work over 5 hours

It depends on the type of school. STPCD applies to maintained schools. It does not apply to academies, free schools or independent schools. If the OP is employed by one of those types of school they must give her a 20 minute break (which need not be paid) if she works 6 hours or more in a day.

Downtome - A change of working hours normally needs the employee's consent. If they are significantly increasing your hours (and agree that they are doing so) I would be looking for a pay increase to match. So, if they are taking you from 30 hours per week to 35 hours per week, I would expect an increase of around 17%. Are you in a union? If not, it may be a good idea to join one and get them involved.

Thank you.
The problem with having a break is that I would have to kick them out and lock the door. That's unhelpful with the type of students I teach.

I sort of saw the early finish as being the break after 6 hours. Would that work as an argument?

I'am in a Union but they say to speak to the Head first. Which would be fine but I don't really know where I stand with the contract. I only have by old one and a letter to say they were making me an unqualified teacher. Didn't get a new contract.

I sort of saw the early finish as being the break after 6 hours. Would that work as an argument

It wouldn't work as an argument for your employer. The break must not be at the beginning or end of the day, so finishing early does not count as a break. However, if you had your break, worked another 30 minutes then finished for the day that would be fine. But the break is your entitlement. If you don't take the break that is generally up to you.

Didn't get a new contract

In that case the old contract still stands for most things apart from the fact they have now made you an unqualified teacher and any other changes set out in that letter. However, as you are being paid for 30 hours per week starting at 8am, that is now your contracted hours. Similarly the lunch allowance may well now be part of your terms and conditions.