mice are straightforward. they travel 10-12 meters around the nest and normally spread as a population from home to home.
If you ever see droppings or a mouse:
1- open the kickboard of the sink units and see if there are a lot of droppings
2- if you live on an upper floor, speak with the flats below, the ground is normally the gateway for mice activity
3-if you live on the ground the mice may come from the garden so check the perimeter of the building for damage on the masonry or if the airbrick need meshing
4- normally mice travel easily between terrace home under the floorboards, so please approach your neighbours and invite them to check for dropping under the sink unit
From there there is no magic, if you do not want to suffer from mice, you either need to kill them before they reach you (that would be the job of your next-door neighbour), or you need to stop them from reaching you (you need to block the access points that the mice use to get into your living space.
for small holes/gaps: steelwool is readily available from most hardware shops then you cover it with sealant to keep it in place.
For larger gaps, missing side kickboards, they can be patched with hardboard
Basically, it is down to being thorough, and proceeding methodically from one side of the kitchen, do the kitchen units, the gap under the dishwasher, the gaps inside the sink units, the gaps at the back of the fridge and washing machine. Seal around the boiler copper pipes. When you are done, it should be as if you would be living in a glass bottle.
When the kitchen is done, follow the walls and keep on doing the mouse proofing in the remainder of your home until you reach the point in the kitchen when you started.
If after the initial mouse proofing you still have activity, it means you overlooked something. So look again until you find the weakness. A fitted-in dishwasher is possibly the hardest thing to proof. So in doubt, pull it out and get the proofing done directly at the back of it, then push it back in.