The self-checkout at Aldi is a godsend. Way too many times I've been on my lunch break trying to buy a sandwich and snack, only for some old git to be using the time at the till to have a chinwag with the cashier!
By all means, have a chat with the cashier, but not when there's a massive queue of people waiting behind you! Also, you know those shelves near the window with the sign saying "Pack here"? That's not a suggestion. Pack your shopping away from the tills so people can keep buying stuff.