House buyers on 3rd survey

They're planning to gazunder you. It's a buyers market at the moment due to
1 uncertainty caused by Labour/Reeves
Useless estate agents
Greedy solicitors halting your purchase plans/offers when your buyer drops out and you become "unproceedable"

Don’t focus on gazundering it’s unlikely that a new survey would be done in that case, more likely finance problems.
I sold a property, after exchange was agreed it took over 3 months for the money to arrive. It. Was frustrating then everything happened in a hurry.
No point in cancelling the deal now nothing much going to happen until spring.

I'm certainly not thinking of/advising on cancelling the deal now. Just keep open to new would-be buyers having that look-around and maybe you'll have one already lined-up in reserve (knowing that they are on a "waiting list" so to say) in case of need.

Once you're as far as exchange - then they'll have a date they HAVE to meet. It's my understanding they could be penalised noticeably if they don't meet it. People are obliged to have the money to hand basically at the date of Exchange. I'm the only exception I've heard of to that one - ie when I bought my first house and I had to pretty much "beg/borrow/steal" to have the standard 10% deposit available (to lend in my case and then I got it back - as I wasnt the one providing that deposit in the event...long story/very rare circumstances).

My solicitor was literally there on the doorstep of where my deposit was going to come from literally on the day of Completion virtually knocking the door down of the "provider". Fortunately they did have everything together and she re-emerged with that deposit in hand. Me - my intuition was telling me it was going to happen according to plan okay and my furniture was all there in a removal van and driving to the door of my new house ready to move in. My back-up plan being "The windows were all still single-glazed and I could get into the back yard and was sure I could find a brick from somewhere to lob through the kitchen window if need be". Fortunately finding a brick wasnt necessary in the event....

Yes, same happened to us and then we were gazundered. In retrospect we should have stepped away but we were so close to exchange and so emotionally invested that we rolled along with it. That is what they are counting on. What we should have done is refuse the last survey and call their bluff hut hindsight is a wonderful thing