It’s a UK. When speaking about the United Kingdom, the letter U has a consonant sound (like "you"), and therefore takes the article "a".
It’s a UK..., so we say a UK company, a UK resident, a UK student, etc. When speaking about the United Kingdom, the letter U has a consonant sound (like "you"), and takes the article "a".
We are a UK company that provides software services.
We are an UK company that provides software services.
The rule for using a or an is based on pronunciation, not spelling, and the individual letter "U" has a consonant sound (we say a U).
How long does it take to apply for a UK study visa?
Following the same convention, we say a united..., a United Kingdom citizen, etc.
The challenge required a united response.
You can buy a United Kingdom government bond that matures in two years.
A partial list of abbreviations that also begin with the vowel "U" but are preceded by the article "a":
