i could strangle those mice!!!!!

I had rats in my workshop a few years back.
I put "bluebait" down & every day it would go. Eventually the bait was left untouched.

I moved to a bigger workshop & when I came to move a sheet of ply that was up against the wall.......there was all the bait.
I don't know if the cat got them all or whether they ate some of the bait & stored the rest.

We had a family of mice move into my home just before November took me 7 traps and 3 weeks to get rid of them. 

I had the same thing a few years ago.  One cat did the job in a couple of days.  The cat is long since gone and hunting mice in the afterlife, but I've just bought another who looks promising.

I quite like mice in the compost bin as they make a wonderful job of aerating it. If left they will do a good job of making it resemble a swiss cheese in no time. The compost seems to cook quicker with them on board. Like you say though they could migrate to your plants but you could let them do the magic on your compost and then evict them. If you give the  compost a really good watering from the top they will leave as they don't like a wet bed   

The mice currently in my greenhouse  are managing to nick the bait without springing the trap 

I've pressed the WW choc raisin bar really firmly into the trap this time.  I feel a heel but I daren't put plants in there until I've got rid of the mice.  All my plantlets and seedlings are crammed into my small greenhouse at the moment

I shall try some peanut butter. Smooth or chunky? 

It's soul-destroying to find trays of seedlings eaten to stumps. I once lost all my brassicas to mice which I had propped up in the shed window

We have loads of moss. I've set the chickens on to it. They make a fine job of scratching it up