On 09/08/2019 21:20, newshound wrote:
Strip of something white and water resistant under front edge, e.g.
slice out of cheap plastic chopping board. And fix the unit firmly to
the wall.

(I'm assuming it's the floor sloping?)

Floor sloping....yes.

I have some off cuts of white UPVC window trim and I am sure thats about
1 cm thick, I will look at that tomorrow. That could be ideal.