i currently have a 40 hr per week job but unfortunately I am not making ends meet. Would a second job incur a lot of tax?

Hi ali welcome to the forum

You are already working full time. Taking another job means that you will also be working weekends too. This means that you may not have any time to recharge yourself. You can consider the second job for a short term, but longer term if you are not able to make ends meet with a full time job, you either need to look for a job that pays you more or cut down further on expenditure.

Income Tax is not per job. It is based on your total income - whether from one or more jobs is irrelevant.

HSP is right about the tax. But what that means in real terms is that your personal allowance (the amount you can earn before you pay tax)will be taken against your main job so all of the money you earn in your second job will be fully taxed. So you will pay 20% in tax on all of your 2nd job.

If you can get 5 independant jobs , one for each working day, you will pay 20% PAYE, but no National Insurance.( unless it is really well paid, and I suspect it is not).
PAYE is a cumulative tax (all gets grouped together) but National Insurance is "by employment" and you get a NI free allowance for each job. 8 months late but it is true.