Lawns should rest in winter, so walk on them as little as possible. Heavy use in wet weather can lead to soil compaction and cause lasting damage to your lawn. Damage to the structure can often happen if the top layers of the soil have thawed and the ground below is still frozen. Using a lawn covered in frost can also cause damage.
As the lawn no longer needs to be tended in winter, there is finally time for maintenance of lawnmowers and other equipment. Thoroughly clean the lawnmower. Replace worn blades if necessary.
During a heavy snowfall, do not pile up too much snow on the lawn. The lawn suffers otherwise, as it cannot breathe under the excessive load of snow.
Voles can cause severe damage to lawns as they usually lay their tunnels relatively flat just below the surface of the ground and the animals gnaw on the roots of plants. The overlying soil is slightly broken upwards.
Ask at your garden centre now for a suitable product to tackle this.