When we moved onto our current house over 20 years ago, there were various signs that there had been a mouse problem.
As we needed to decorate from top to bottom anyway to make it habitable, we blocked every single gap on the place (around pipes, along skirting boards, vents etc) and so far no mice have found a way back into our living space.
They are still in the loft space, and have been accompanied at various times over the years by rats, squirrels and bats, and I have very occasionally heard scratching behind the skirting, but so far our main defences have held.