Two different lenders, same surveyor

Me and my partner are looking at doing additional borrowing during our remortgage to pay our HTB off. We’ve done the RICS valuation and they valued our flat at 435k and need to pay HTB 25% on that.

We went to Nationwide as they had better rates but when they did their valuation through Countrywide Surveyors, they valued the place at 410k. This would leave us with a 25k gap that we are unable to pay presently, so we decided to try another lender - NatWest.

They’ve supposedly valued the flat at 441k which is great but apparently they’ve want an in person valuation to sense check the value, and it seems they are using Countrywide Surveryors too 😅😓

What exactly is the likelihood that we will get two different valuation sums and that the second time around it’l match NatWests proposed value?

We’re not in a position to pay 25k and if the flat gets valued at 435k or slightly above we’ve be getting a 90LTV with the additional borrowing.