the sad thing about this too is that you have a different tax code for a second job and you get taxed massively
That's not true.
The tax bands are the tax bands no matter where your income comes from. If you have two jobs you can either ask HMRC to split your code or you can have your code all on one job, they don't seem to mind how you do it.
The code is about your tax free allowance which is £12,500 in 2019 (April). So, if you earn, say £15,000 in job 1 and £4,000 in job 2, you may as well have all your tax free allowance on job 1 - then you get £12,500 tax free in that job, and taxed on £2,500 (at 20%), and taxed 20% on job 2 on the £4,000. (this all assumes you owe nor are owed any tax)
If, however, you had one job that paid you £19,000, you'd still get the £12,500 tax free allowance, all on that one job, and still get exactly the same 20% tax on the remainder, which is exactly the same amount - £6,500. The take home would be exactly the same.
In the 1980'w there was some weird marginal tax thing that meant second jobs got taxed differently, but that is long gone.
I think what people don't realise is that you only get ONE tax free allowance of £12,500 (pa). It is usually applied to only one job but HMRC will code you so each employer uses part of it if you want them to (no idea why you would though I did that when I ran my own company and was employed as well as it meant I didn't underpay my tax by accident which I hate doing as I hate owing tax).
If you draw a pension and are employed, they nearly always apply the tax free allowance to the pension rather than the job, so it might feel that the job is 'taxed higher' but it's not, it's taxed the same as if you earned all that money from one source.