Best way to fit a bath panel?

Question

need to fit a new bath panel made of plastic but my wall is uneven and making the panel not fit at the over end of the panel

Answer 1

HOW is your wall uneven?  Are you installing the new panel over old stuff? What are you calling the "over end" of the panel?

Answer 2

Offer the panel up to the wall and follow the profile of the wall and trim the panel. If you dont fancy that, or it is only slightly out - chase a groove in the platerwork to allow the panel to settle in. (Not easy if the wall is tiled). Use a fine saw or sharp knife, depending on the thickness and be careful not to put too much pressure on the panel as they are apt to crack.