he hasn't got his lump sum yet
No, and your son isn't at uni yet- almost a whole year to go! And as you know, that's not the point - it's all about his or your unwillingness to help a stepchild.
Work experience is really good for all kids. Employers do notice the difference. However, some courses make it hard for students to work during term time. One of my DCs did a pure science degree which meant lectures and lab work 9-5, every day, and lab work looking after experiments at weekends. They did though work at weekends throughout the 6th form, and all holidays while at uni.
I don't think anyone disputes this.
Most students manage by working when they can, using the overdraft facility they get from their current bank accounts, and if they are really stuck they can apply for student hardship funds via their uni.
But many parents do top them up, even if it's loan to be repaid. It's a while now since my DCs graduated but at the time we paid one of them £250 a month for living expenses and their loan paid for their rent. They paid for their own books, clothes, transport etc out of earnings from holiday work and money relatives gave them for birthdays etc.
If we hadn't been able to fund them either we'd have made sacrifices, or they'd have gone to a local uni.
I do know families who sold their houses and downsized in order to pay for their kids to go to uni.
Going back to the OP's post, there are