I agree with this.
What is wrong with him taking out a loan, getting a job beforehand and saving (my children did both)? Why are you busting a gut to do overtime?
Is this something he actually wants or is it being driven by his parents?
Tbh, I wouldn't go today.
For everyone's sanity.
University open days are not that crucial and, if he's ill/rough and you're pissed off with him, are any of you going to actually get any benefit from it? Essentially, all of the info available at open day will be available on the website but you'll (he'll..?) also get a bag with a bottle opener, a lanyard, and some other pointless crap. They're a marketing event to encourage students to attend.
I'd leave him to it and use the day to do something more enjoyable with your husband instead.
And I say that has someone who has been to university twice (UG and PG), with one graduate child and another who has just started her first year.
And they managed just fine without me doing overtime, working 13 days straight, hovering over them during A level revision, forcing them to attend open days... that's not to say they weren't supported but they were supported when they wanted it. They were self motivated and driven to achieve it. Not because I micromanaged them.
Because, if he goes to university somewhere 3 hours away, he is going to have to be self disciplined and motivated anyway or all your input will have been for nothing anyway.