How often will I need to clean out the ash from my stove?

This depends on many factors including wood quality, stove size, standard of installation, stove efficiency and user operation.
However, for an average evening and weekend user expect to have to clean a multi fuel stove out at least once per week and a wood burner may only have to be cleaned out once a month.

Please note this is very approximate and using paper to light the fire will increase the frequency of cleaning out.