Advice needed please - a bit complicated but I'm in a bit of a fix

[pleasestoparguing]

I have been working at a school for 2 1/2 years on supply - I asked recently if I would be going on a contract next year and they said they could offer me 0.4 - I said I wanted more as since I would be working every morning and getting supply rates for the extra hours and I wanted all the hours I worked on the contract.
On Thursday I got a letter (written in Wednesday) confirming futher to 'our conversation' I would be working on a 0.4 contract next year. I was a bit pissed off as i had said I wasn't happy and it seemed like a fait accomplis.
Meanwhile I had applied for another job in another school but has assumed I was unsucessful as they had said if i hadn't heard by Wednesday I should assume I was not successful. So today I said to our school secretary ' I got your letter thank you.'
I have just this afternoon received an email inviting me for an interview at the other school.
I have not formally accepted any offer from my current school but there is an implication that I will stay - what is my position in terms of applying for this other job?
I know it will affect my HTs attitude as she will feel I have let her down - well I have but she hasn't been entirely straight with me and there are other issues at the school which prompted me to want to leave for instance her shouting at the staff including me when she's in a bad mood - the thing is if I don't get the new job I want to keep my current one but clearly she'll be pissed off with me and then I'll get a hard time from her .
I was wondering what my actual legal poisition is and what I should do - I really want the job at the other school as it's offering 0.7 on contract which will make a lot of difference financially.
Bugger bugger bugger - please help.

Yes just ask them to please hold off on references until after the interview, you don't have to explain why.
The good thing about teacher interviews is that you know there and then whether you've got the job.
If the interviewing school are quick off the mark they can ask for an email/fax/phone reference while you are still at the end of your interview.

It's not being dishonest behind her back, she's made you an offer you haven't accepted yet so you are a free agent until you do.

You aren't abandoning the children, especially not if you only teach 0.4 anyway (that isn't meant to be harsh, I'm sure you do an excellent job).
This shouldn't be a matter for your conscience any more than it is a matter for the head's conscience - and she doesn't seem too worried, if she was she would be fair, kind and decent to the staff working at her school.

It is good to be a conscientious teacher but you must also put yourself first because nobody else will.

I think most people, even evil HTs, understand that someone would prefer a 0.7 to a 0.4!

Can you go to her and say, "while I would be very happy to take the 0.4 here... love the kids, school, etc etc - there is a 0.7 post that I really have to apply for as we need the income".

Just present it as simple economics.

I think you would be tied into the contract to give the three months notice after you start work. So say you start the .4 on 1st September that's when the notice would apply from. That woud be my opinion. Accepting a contract and then backing out and not starting isn't a good thing to do of course, but as far as I know they can't enforce it.

But the op hasn't yet signed the contract Viviennemary

Thank you everyone it really makes a difference hearing this from other people - I know you're all right and I need to do what's right for me, I might not even get this new job but I have to give myself a chance. I was quite depressed at the prospect of staying where I was so if I have to of course I will as we do need the money but we need the extra monet more and of course I shouldn't stay somewhere I 'm not happy for any longer than I need to.
I've just got to pull myself together and really go for this new job - I'm going to have to tell my HT I'm going for an interview as it's on a day I work - so I'll lose a day's pay for it but it's still worth it just so I know I've given myself the best chance. But thank you catsrus that's a real reason why I'm applying and so it's not unreasonable to tell her -
I'm still a bit scared but I've got to do it but knowing I'm 'allowed' to will make it easier.