Thanks for that info @NoWordForFluffy that is really useful to know as wasn't sure what the procedure would be. I may lose some money yet, but I won't know until the lender makes a decision. I am guessing the solicitor has some sort of indemnity insurance for this type of thing too.
There is a chance my mortgage lender will not give me the mortgage now and if this is the case, because I was porting a fixed rate (with another 5 years on it) I may have to pay their exit fee, which is just shy of £5k.
This particular lender also slightly hid the condition, rather than saying "your mortgage offer is agreed when this condition has been met" and highlighting it, they said the offer was agreed subject to conditions, which is the bog standard way all other companies word it when there are no additional conditions apart from standard ones, so I can see how it was missed. Apparently they have changed their procedure now as to how they highlight issues, so I cannot have been the first person this has happened to.
I also lost my buyers soon after the lenders valuation back in Jan, so I think when my solicitor picked up the baton again, it would have looked like all was fine. But, essentially, this is what I paid her for to read and check the small print of the sale/purchase (she has taken her fee on completion already)
Anyway, I am in, the house is lovely, the kids are happy, so it could be a lot worse. I really do dread to think what would have happened if my parents hadn't been in a position to help.