Looking for some guidance on a valuation on a new build house mortgage

pw2911

Morning all,
I've just signed up to this forum.  I've used it for years and it's been extremely helpful.  However, I now find myself in a spot where I can't find an archived thread that helps - so any guidance here will be a huge help.

My wife and I reserved a new build house here in Scotland (via Cala Homes) earlier this year and over the past few weeks we've had a lot of issues regarding the mortgage.  Long story short, the surveyor that the lender used has valued the property at 50k(!) less than the selling price Cala set.  Cala are livid as apparently this surveyor is notorious and they've had no issued with any of their other plots that are of a similar size and value to ours...but that doesn't help with our plot as the damage has been done with that valuation.

Initially we were going to pay a 25% deposit and were approved in principle for a 5-year fixed term mortgage at 1.6%.  With the new, reduced value, that £50k delta means we need to drop to a 20% deposit and the 5-year fixed term increases to 1.77%.  To be fair, Cala are offering us an additional £12k for our property (we were doing part exchange) which allows us to make the 20% deposit (on top of the £50k extra we need to pay).

We've saved hard for this and fortunately we're just about able to afford this, however, my big concern is this initial valuation from the lender - will this impact the value of the house going forward? Or, because we're paying the asking price and the other plots are all selling for the higher values should we be ok?

Apologies for waffling on, hopefully that makes sense and any guidance at all will be a huge help.

Thanks,
PW