Hi, thank you for your response.
Honest answer is I don't know. The mortgage company is Santander Bank. I don't see any reason why they could reasonably refuse a lump sum payment, so, I would like to ask the question on the basis that Santander do accept lump sum payments.
Hope my response is sufficient.
It's an interest only mortgage.
I've checked Santander's website and it seems lump sum repayments are acceptable.
Hope that assists.