OP, I can't help but think you're being deliberately goady now.
You're talking as though the situation was thrust upon you, but the truth of the matter is that it's all down to decisions you've made. However misguided those decisions were, you had full agency.
My memory of the timeline from your previous posts is sketchy, but I believe you were fully aware of his immigration status from the beginning of your relationship. From an early stage you seem to have cast yourself in a role of "saving" him from having to return to Pakistan.
You've said also that he's trying to better himself and shouldn't be judged for doing unskilled, minimum wage, work. But (again, based on memory) he's been in the UK for over 12 years now and hasn't managed to work on his written English, pass his driving test, or improve his employability in any other way in that time. Things aren't likely to change in that department now.
You talk, in your own words, of being forced to live in a "poky" 1 bedroomed flat with no heating, but have posted elsewhere about a foreign holiday just a few months ago, and surviving on takeaways rather than cook your own meals. I'm aware you have some health conditions that restrict your energy and capacity, but this is something your partner could be doing.
All of that aside, the fees aren't going to go away. So the choices are to increase household income by your partner finding extra work, or to reduce your household outgoings. The family's circumstances in Pakistan aren't the same as they were 8 years (oer more) ago as both sons are now working and don't need the same level of financial support.