Any question answered...

Fox, try the high pitched noise emitters, I have one which claims to pulse the electric circuit which also annoys the mice apparently

I was a bit skeptical but it seemed to work, we have been away for 2 weeks at a time and still no mice

they work.
tried traps/poison but they only keep them away for so long in victorian terraces where they can move from house to house easily, i used to hear them coming down the wall cavity from the flat above in the middle of the night.
have 3 noise plug thingys throughout the house. mouse free for 6 months.