I have a degree in international relations with politics, how do I get a job at a British embassy abroad?

You have to pass the civil service entrance exams first. If you want to be fortunate enough to enter the diplomatic corp you'll need fluency in at least one other language. No, you can't choose where you go, it isn't a holiday.

No, you don't usually have a say in where you are posted. You have to go through the civil service entrance exams first as well.

If you wish to work for the Diplomatic Service of the UK, you will be (according to www.faststream.gov.uk) 1) British National (with some more details on lenght) 2) In possesion of 2:1 honours or above in any discipline You can then apply... After security checks and interviews and such, you will most likely find yourself working in the UK for a while first before being posted abroad. Foreign postings will generally be for about three years, and you do not have a say in where you can go. After having gone abroad for three years you can return to the UK for a while before a new posting comes along and off you go again... Obviously you could help yourself by speaking another language fluently - for example, if your Spanish is fluent it would obviously make sense to send you to a Spanish speaking country. This is the only way in which you can make your preference know in a "diplomatic" way

I have the same degree as you in IR, a couple of my mate's parents are diplomats, under the impression I got from speaking to them, this is how it works. You submit a preference of countries you would like to work in. Let's say you pick France, Uganda and Chile. You'll probably get one of these three. Every three years you change consulate posts, and I also believe that it depends on how high ranking you are as a diplomat. Probably the best go to countries like the united states or other non-peripheral countries. Good luck.

I thought you embassy people were there to offer advice...you wouldn't be much bloody good in an emergency abroad

Two ways - either join the FCO, or get hired abroad directly as a local hire. Local hire work isn't however going to be attractive - mostly administrative work. It is exceptionally competitive to join the FCO. They are looking for people with a strong academic record, very good communication skills (the kind of communication skills that impress people), an inquisitive mind and an adaptable personality. Foreign language skills and work experience overseas helps. I cannot speak for the FCO, but where I work eople compete for diplomatic slots internally. So naturally it is harder to get to Paris than, say, Port Morsby