Its underneath the rear off-side(drivers side) wheel arch if you lay on your back infront of the wheel and look up you should see it. Held up with two bolts on a plastic mounting. It has been mentioned on here before, try a search and see if any other threads help.
This one may bout page 2 or 3 i think http://www.landyzone.co.uk/lz/f9/fuel-filter-td4-24449-1.html