You can find out how much your neighbour paid for their houses, or how much your house was paid by previous owner by going to one of the following sites:
www.houseprices.co.uk/
www.nethouseprices.com/
www.zoopla.co.uk/house-prices/uk/
www.mouseprice.com/
All the sites above are free to use, and you don't even need to register or sign up with them. Just type an address and do the search. Some of the sites also provide free home evaluation, e.g. www.mouseprice.com/ .