Lifetime ISA - withdrawing exactly at 12 months - is it worth it?

I haven’t yet been in this position but is there a possibility that the mortgage company would continue to provide the same level of mortgage but allow you to draw some of that down in cash? Or have those days not (yet) returned?

I know that pre 2007, some mortgage companies were offering over 100% mortgages with the balance being used to furnish the house, which I appreciate is very risky from their perspective. However, if the mortgage company has agreed a mortgage of £333k, would they be willing to still provide that, albeit £10k into your bank account (a bit like in the sense of a remortgage) and then you use your £10k LISA to find the completion?

Apologies if i’m Talking rubbish here!