I was motorcycle courier years ago which is much the same thing.
Before you start worrying about Tax I would be worrying that you get enough work to cover the cost of the van lease.
what is the minimum amount of work he would have to do to get the monthly lease payment.
I wouldn't go trying myself into a lease contract without a guarantee of work.
Oh and BTW
Self employed is probably UK mail getting out of employer responsibilities to staff, and you may find that he will be working for less for minimum wage during some periods.
Really really go through the contracts, this could end up costing him money instead of him making any if he's not careful
Before you start worrying about Tax I would be worrying that you get enough work to cover the cost of the van lease.
what is the minimum amount of work he would have to do to get the monthly lease payment.
I wouldn't go trying myself into a lease contract without a guarantee of work.
Oh and BTW
Self employed is probably UK mail getting out of employer responsibilities to staff, and you may find that he will be working for less for minimum wage during some periods.
Really really go through the contracts, this could end up costing him money instead of him making any if he's not careful