A tenner?
£100?
£1000?
£10,000?
(If it were "disposable" income)
£10 - go to the French deli and get something delicious
£100 - hiking boots. Or a seat package at the theatre - show, chocolates and champagne, yum!
£1000 - skydives, so many skydives
£10,000 - see how far I could backpack around South America, starting wherever the cheapest flight landed