Complicated new job after exchange problem
I'm currently on maternity leave, employed in a school and currently due to go back in September. My husband and I are waiting to compete on a new build property eta middle of June and exchanged contracts last month. A few days ago I was offered a job in a nursery where my daughter can also attend. It means better hours, and I would be spending next to nothing for my daughter to attend nursery vs over £1000 a month if I was to remain in the school. I wouldn't be starting this new job or even resigning from my current job until after we complete on the house.
My new job want me to do all the relevant work checks like references, DBS, identity etc now. My question is, am I going to get in trouble with my mortgage provider? The salary is a little less a year and I would be starting on a 3 month probation but I would be saving so much more money a month with this new job which I plan to start at the end of July. Should I tell my mortgage provider and risk them pulling the mortgage offer or tell my new job I can't take it as I can't complete the checks until next month? I'm with Leeds building society and live in England if that helps.
Edit: If I were to tell my mortgage provider aboit my new job, do you think they would accept the new terms?