At any one time I have about £100 in £20, £20 and £5 notes in my wallet. Everything else is in my bank account.

As for buying things, I very rarely buy something physically - the money is there just in case a friend forces me out and I need a fiver for the bus, or a tenner for the cinema or food. When I do buy something it's online, and aways over £100 in total (which I do every four months or so).