I've been getting it wrong all this time. I've been writing Gov.UK (or GovUK on twitter if I don't want to include it as a link). I've stolen this explanation for why from the Guardian style guide because I'm too lazy to type it:
"Use all capitals if an abbreviation is pronounced as the individual letters (an initialism): BBC, CEO, US, VAT, etc; if it is an acronym (pronounced as a word) spell out with initial capital, eg Nasa, Nato, Unicef, unless it can be considered to have entered the language as an everyday word, such as awol, laser and, more recently, asbo, pin number and sim card. Note that pdf and plc are lowercase."
However I do whole-heartedly agree with your pronunciation: “guv dot yew kay”. I hope this finally puts an end to those who habitually refer to the website as "govv dot yew kay".
