Worst case scenario, go find yourself a small (very small) set in the open, where you know there is a bunny or two, take a shovel and some red bull, put ferret in (start early morning), and hopefully bolt rabbit into net and celebrate as hob trundles out. If not, first wait, squeek, listen at holes etc etc etc, and if that fails drink red bull and dig a really big f*****g hole, really carefully. Then go home for tea.