Cutting along the bottom of a wooden bath panel?

[JtB]

I've just had a new bathroom floor laid and I now need to cut about 8mm off along the bottom of a 18mm thick wooden bath panel. Can anyone please advise the best way to do this?
Thanks,
JtB.

 

[masona]

Is the bath panel made of MDF ? if so cut it outside because of the dusts.

A circular saw with the guide runner is ideal, score with sanding knife to prevent chipping on edge or leave at least 1-2mm to finish off with a plane. A electric planer is possible or a Jet-Cut hand saw.