It is important to keep trying. Not everybody will make it first time, I did not when applying for Tax Professional Training, but I was put on a reserve list and called up later. Many do not make it first time but they do make it second time round. The process for recruitment can be long, but do not get disheartened, this is to give everybody the best chance of being accepted. If you can, get feedback and consider it for future applications. Feedback will often point our your weak area that can easily be improved with a bit of practice. If you do get on a training programme, be aware that though tough, they want you to succeed and will do everything they can to support you in achieving the end goal. Do say if you need extra support, they cannot provide it unless you tell them you need it. I am dyslexic and they took this into account for exams providing computer rather than writing and also extra time for reading.

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!