A few of my cars, and the heating in one of the warehouses, runs on waste oil, at the moment I'm okay for supplies but more is always useful.
I've noticed that Bookers buy back the 20l drums they sell for £2 in vouchers (10p per litre), so just to make it fair I'll offer £4 (cash) for a 20l drum (20p per litre)
This is probably of most interest to someone with a cafe/chippy/burger van unless you have a BIG family and a lot of fry-ups
Vegetable or Sunflower, makes no real difference to me, seems to run on anything (even White Spirit, but I have to pay tax on that). Can collect if that helps depending on quantity.
Oil only, no solid fats.