I would give him the 20 pence, then follow him to the fabled establishment that sells sandwiches for 20 pence. Then I would strike a deal with the proprietor whereupon I would buy as many sandwiches as he can make, then drive around town selling them to building sites, shops, schools and wherever will take them for £1 a go.
You are all wrong ..... You should him to Toolstation ! Apparently, he can get free tea and coffee, biscuits and probably a foot massage .........