I get asked this question all the time why should I buy a co.uk domain name if I run a British business ?
The answer is simple if you use the wrong extension you are going to have lots of leaking traffic and you will regret that you didnt buy the co.uk at the start. I understand it might not be in your budget but your happy to spend £100,000 on a media advert in London but your not happy to spend £100,00 on a domain name that you will own for life with unlimited money earning possiblites thats why domain names are very valuable its like owning the best property.
If your a serious company and you operate in the UK or you are a company that operate abroad that want to venture into the UK buy a premium co.uk and dont look back.
I will be running a YouTube channel talking more regarding these subjects are more.