Why are you worried? If it's not drinking water, it's ground water, the end
If you're concerned that it's a leak you're paying for, note the reading, shut your water off at the stop tap overnight, tell other house occupants to expect eg the toilet not to flush more than once, and then read the value again in the morning. If the meter's moved appreciably, sort it. If it hasn't, don't worry.
A thousand litres of water is something like 3 quid. If it's leaking a litre a day, it's £1 a year; only you can decide how much you're willing to pay for a leak before it's worth the upheaval of digging the meter up