Plan 5 student finance repayment

I currently have a plan 2 student finance loan for my undergraduate degree in 2018, and a postgraduate loan from my masters degree in 2021. I wanted to do a PGCE this year, however, I am getting very stressed and confused about the student finance aspect of this!

As the undergraduate plans for 2023 have just been changed to plan 5, which has a different repayment threshold, if I take out a loan for this, it would seem I would have 3 different payments with 3 different thresholds all being paid back simultaneously. This would increase my payments to 25% of my income once the plan 2 threshold is hit (which will be immediately as minimum teacher salary is £28,000), which seems highly unreasonable with tax, national insurance, and council tax all to pay on top of this 25% payment. Is this how this plan will work? because if so, I will not be able to afford the PGCE due to this change, as it would add a significant amount to my student loan repayments per month.