Done a little more maths on this subject and based on £1.35 per mile, and theoretically maxing out (or close to) your driving hours along with the other obvious things like VAT back on fuel etc, I ended up with a potential £650-£700 per week.
But as said, pension, holidays and sick pay etc, bring it broadly in line with a decent PAYE employment.
I suppose it suits the kind of person who likes a bit of control over their working life and enjoys blinging up their wagon (which I wouldn’t knock) 