On the subject of .co.uk and .uk I am selling lots of .uk to USA/Overseas buyers and they don't want the .co.uk version from me?
Also .uk domains rank just as easy in google uk as the .co.uk version.
If I was starting a new brand and had both I would run with the .uk version especially if advertising offline as less chance of leakage to .com version, if someone sees my advert or poster, banner etc for mywebsite.uk as opposed to mywebsite.co.uk. then .uk is easier to remember and no reference to .co, where as .co.uk could end up as .com especially if my browser auto adds, inserts or suggests it.