Ответ:

1. I haven't got much money in my purse/wallet. I need to go to the bank.
2. Can I pay by credit card or cash?
3. Have you got this T-shirt in a size M?
4. Can you tell me the price? Is it £20?
5. It's usually £20, but it's only £15 in the sale.
6. I'm sorry, we only accept cash.
7. Here's £20. Thank you. Here's £5.