We're last minute - as in just decided - having some of my daughter's school friends round for trick or treating and then some dinner. What can I throw together with literally no prep time? I'll be at work all day (though can nip out to supermarket or M&S) and back 5 mins before guests arrive. Something for 6 adults and 4 kids that I can whip up in about 10 or 15 mins. Also, any ideas for nice nibbles that I can buy. Please help.