My experience says:
.co.uk is just under .net for anything with a good market in the UK. In some cases it can be higher than .net bc/ it carries much higher prestige than .net in the UK so you can actually sell them for more to UK end users than a .net will go to any end user.
.org.uk pretty low, but worthy of looking at for domains that fit the ext and are regged in many other country code extensions (ie are strong at a country-level)
.me.uk useless