Colleges and Universities mainly use the .ac.uk domain names reserved exclusively for them. But they can also use other domains (urls) at their description and other training providers frequently prefer to use .co.uk or .com addresses for their websites and emails.
But what if the domain you want isn’t available? Well, you might still be able to pick it up. Some addresses aren’t used, people just buy them with a view to sell them. They cybersquat on them. Agencies that do this will offer urls at exorbitant fees. Think carefully before paying them. How much are they really worth?
Some addresses have been used but are going to expire for various reasons. It might be the businesses has ceased trading or changed business direction. In that case you can buy them once they are available.