Thanks for your help yesterday VainOz. You have helped point me in the right direction.. The reverse lens option looks a touch scary to perform out in the field tho.
I found another one, whereby you use an old binocular lens on the end of your lens which seems less risky, but probably causes some nasty distortion.
I'm going to mess around with these while waiting for my filter and then try out some of the len tubes later to see what performs best.