When I moved from Pakistan, I was told by many that the only jobs I can get is working in a shop as graduate careers aren't for us. The fact that I didn't take their word made such a difference. Self-belief is the first part of the equation and once you have that, top it up with doing your research and acting on it as actions make the most difference. There is a lot of material available for applications and what it takes to be a civil servant at HMRC. Have some time to read and understand it before applying. Lastly, overthinking is not your friend, so my advice is to do your thinking but DO NOT over think and take actions to make a plunge!

Keep your mind and eyes open as there are are so many opportunities

Look for opportunities to build your skills, develop your talents and reach your potential. Sounds very wordy but learning is a lifelong journey and we never know everything I have found that trying something different has kept me happier at work and given me a sense of self satisfaction. It doesn't have to be work related it can include learning any new skill from sewing to pottery. At the moment I am currently spending 30 minutes a week completing learning around marketing and social media which is providing me with skills to better understand my role and that roles around me.