thin skim for block wall ?

[ChippyJoe]

Moving forward well with the expansion build of the garage/workshop.

Walls are a combination of previous block, brick sections, and new block section using up mixture surplus of spare blocks of several different finishes - each 'area' varying quite a bit in finish surface.

Plan eventually to give all the walls on the inside a white paint, but short of mortar rendering of all the walls easy to apply for an amateur, reasonably priced thin skims (say just a few mm's) to run over the walls with before painting, to make the finish overall a bit more consistent ??

Any thoughts much welcomed.