What's the point?
Getting a pay rise just means even less TAs. Cos any payrise just comes out the existing school budget. It ends up being totally counter productive. I am terrified at what our head is going to say about staffing for next year. I know she's got a massive dilemma and she's not trying to recruit at least one more TA for next year when I know she will need one to maintain current levels. The staff are already at breaking point and DSs class doesn't just need one TA it needs two. It's massively affecting the whole class.
There has to be more funding. That's a completely separate issue. As much as TAs need to be better paid, there has to a bigger budget to have enough of them too.
Fight the right battles not one which only makes the situation worse not better. I do feel that fighting this battle along this premise will ultimately result in a worst outcome. You have to get it right otherwise the government just do a slight of hand job and dump the issue right back on Heads to sort out the headache and they get away with not actually changing anything nor taking responsibility for the mess.
It's a hiding to absolutely nothing to approach from this angle.