I currently work for the old man and he won't give me any more money !

I have suggested that I go Self employed and work for him as subcontractor whilst having work of my own too.
Own van, tools, invoices, customers, and also working alongside old man on his round.
Who knows bout IR35 ??
Is it possible to do this or are we set for trouble ? (old man has several previous bad history with MR tax)