[claudius]

Five kilometers sounds like a very sane maximum distance for shopping, which is manageable in one hour (two hours round trip). You don’t have to visit every shop each day, as the prices will be roughly the same and you can note new ones as you get to the shop the next time. Walking requires nearly no energy, compared to the standard energy requirements of the human body.

Also note that a bicycle for as little as £20 can speed up transportation immensely at nearly no cost (of course, you might want to invest a further £3 in chain lube, but, well).