If we only did what was comfortable, we would never make any progressions. Challenge is part of growth but if you are your first obstacle, then you will never even try. No matter how ludicrous, never say no to yourself once you remove that impediment then you can start working out what you need to do, if you have the experience or skills, then getting down to complete the application or if you don't have the skills then what can you do to either acquire them or demonstrate you can pick that skill up quickly in the new role. Finally, make sure you read the application and provide them with the information they need to make it easy to appoint you or invite you for interview. The number of applications I see without any reference to the role they are applying for is really disappointing, so make sure what your application says is appropriate.

There are a huge number of roles within HMRC and the wider Civil Service. There will be some that really suit your skills. Where there is a gap, the training and development opportunities available will give you every chance to fill that gap and find that role where you can excel. You will find management want you to improve and will encourage your development, whether within your current role or to achieve the abilities to change to somewhere else you can be better. Self-belief used properly can be your strongest skill.

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!