I'm fitting out a home office at the moment - currently scratching my
head over a drawer unit. Plan is for a worktop to be incorporated
into an alcove (an old chimney breast), below which will be a small
locker to the left, adjacent to a stack of three drawers to the right.
Whole lot is made from maple-effect Contiboard, other than the
drawers which I'm getting as prefab kits from www.woodfit.com (I
bottled out of making them from scratch I'm afraid).

Where I am at now is that I have fitted the Contiboard sides into the
alcove (duly padded out as needed to ensure all corners of the unit
will all be 90deg), and the locker and door is complete. So I just
have a hole to fill with drawers.

The exact heights of the drawer fronts are obviously defined by the
height of the adjacent locker door (allowing two 3mm gaps between the
drawers). Making the drawers themselves shouldn't be a problem
(haven't ordered the bits yet!). But where I'm a bit stuck is where
and how to place the runners. Clearly the positioning is absolutely
critical for the drawers to run freely and for the fronts to be at the
right height. I can't quite see how I'll be able to access the inside
of the unit to mark up screw positions with the drawers closed.

Maybe all will become clear once I have obtained the drawer
components; but I'm sure others must have done something similar in
the past and might be willing to share their experience?

Many thanks
David