Since most of the places I shop do accept most types of credit card, I only bring these plastic cash with me when I go out. Of course, I still carry a few dollars and change for tips or smaller purchase under $1 or the parking meter. It so much easier this way as I don't have to deal with handling 'cash' from the cashier. I just swipe the card, sign and go.
Since there are so many different types of credit card available in the market, you can pick one or two that match your daily lifestyle. If you are living in UK, go check out Co-operative bank's credit cards. They have a wide range of credit cards and you can be sure to find one that suit your need. For example, they have a travel credit card that you can collect travel points besides able to get discount or free travel insurance when you booked your holiday with Travelcare.
So stop carrying too much cash around. Use credit cards.