Mortgage application alomst complete, now new job offer

Pipx

I am in the process of buying a house. I have a 40% deposit (purchase price is £150,000). I have signed the mortgage offer, it is still subject to valuation but that should be cleared next week. I have been offered a new job, on more money, in the same profession. If I hand my notice in with my current employer at this stage am i obliged to tell my lenders (HSBC), and if so is it likely to affect the offer they have already made me?

Thanks for your help