The FCO/diplomatic fast stream DO NOT CARE about your degree in the application process. Their only requirement is that you are able to graduate with a 2:2, and even that is only for appearance purposes. They have a fast track scheme that allows you to apply for the fast stream without even having a degree. The reasoning behind this is diversity. Many amazing candidates will not get amazing degrees from top universities and they do not want to miss out on those people.
Their main focuses are:
- verbal and numerical reasoning and situational judgment, to show that you are capable of handling the written and other tasks they give you to a high standard
- the civil service competences, to demonstrate that you will work well in a team and are able to work in the areas they deem important (ie, working at pace, or making effective decisions)
- your ability to communicate clearly and effectively in person, at interview or at assessment centre.
Everything they do is in order to ensure you have these skills.
They DO NOT CARE about whether you have experience in a relevant field, or language knowledge (with the exception of hard languages). They care more about how you implement your experience.
To give yourself the best chance, I would suggest really focus on choosing a degree you are passionate about, so that you can explore the things that make you tick. I would also suggest stocking up on workplace experience, whether that be a big office, your local Topshop, an internship or a year at an NGO. Also, your best chance of success comes when you have a lot to talk about in order to apply the competences. Do extra curriculars that you enjoy, perhaps that aren't just sport related. Get involved in the wider community, volunteer, take leadership roles wherever the opportunity presents itself.
Finally, it is so incredibly difficult and time consuming to obtain a job in the FCO or the diplomatic fast stream. It's probably the most competitive area of the Civil Service, so PLEASE make sure you are absolutely passionate about it before taking the journey. You're likely to become very acquainted with rejection, so you need that drive.