Hi - I’ve been running Mouse Guard for a couple of years, and have produced a range of resources to help run Mouse Guard games. These mostly duplicate things present in the boxed set (cards, dice, etc), which may be useful for folk like me who failed to buy that when it was available. There are some adaptations for UK-based games, chiefly the types of fauna which may be present.
The resources are available at https://games.gark.net/MouseGuard/