Allotments 4 All

All good ideas have problems, growing broad beans and peas in my greenhouse because they get eaten on the plot, but the little rotters have managed to get into my greenhouse and I now have to re-sow all the above! >:( 
(I wouldn't mind but it is probably the darn mouse I caught humanely in the house and kindly released into the garden!!!)
So any ideas on how one makes a greehouse mouseproof??!! (apart from keeping a cat in there) Or am I going to have to cover everything in there with mesh too? Oh and would they nibble seedlings, or is that my sluggies?!

Ha caught one today, it is now living it's life in a woods near to us! Trap re-set and ready to re-sow!

Lots of mice at my lottie, that's why I sow all beans in balcony boxes covered with fine chicken wire and plant them out once they are up. They don't seem to bother the seedlings.