With many Christmas jobs now coming to an end, there are going to be lots of people finding themselves out of work. Now is not the best time to be job hunting as there is a lot of competition for jobs due to the Covid pandemic. This means that there may be more people than usual going for the same vacancy as you.
You need to ensure you are ahead of your game so that you can give yourself the best possible chance of landing the position. Firstly, ensure that your CV is up to date and includes all of your employment, experience and educational history. Try to highlight any areas that are particularly relevant to the job that you are applying for. You may need to tweak you CV each time you send it out in order to do this. If there are any gaps in your employment, try to briefly explain why. If the issue is complicated you may need to speak to them about it if you get invited to an interview. Never lie on a CV about employment, experience or qualifications as you may well get found out and this would likely result in them not offering you the job or even getting dismissed if you are already working there when they find out.