Buy/Sell Websites in the UK
STOP! Slow down at least and just look at the UK market for a second.
Hundreds of established websites and are offered for sale in the UK every day and thousands of others around the world. Almost all website for sale listings are placed on sites that are automated with little or no regulation or human supervision in place. Only a fraction of these sites will contain any original code and even then it is unlikely that you are the only buyer.  eBay has dozens of established websites on  sale priced from 20pence to 20 thousand pounds. Any of which can be created in seconds.

Established Websites
Throughout the world and in particularly here in the UK there are very few websites that live up to the claims of the seller or the expectations of the purchaser.   Data is often unreliable with website traffic bought and sold like vegetables and as as easy to order as pizza.

Get Real
Web Designers and coders who manage to come up with something original or profitable will not sell their established sites until they have tried every trick they know to make it work for them.