Officially no,
they have to have a signed form from their Nominated Waste Disposal contractor.
Unofficially, they will probably be only too glad to give you a couple of litres.
Just make sure you don't get the drum/can with the 'trap grease',
the oily crap from the 'u'-bend.
Where can I get a couple of litres of used cooking oil? Are takeaways allowed to give it away?