Just a quicky Ian, I tried using cling film - just once. I found I was for ever ducking and diving, trying to avoid the light reflections from the film. I gave up and never used the stuff again, preferring to pin the parts direct to the paper plan....As long as you are careful where the glue goes, you don't really need any covering, as such.
For most of the build, the wing ribs etc. will go on top of the leading and trailing edges, as will the fuse. ribs , so no real need for any protective covering. But do what you feel happy with and good luck with the model. Just make sure everything is nice and square and plumb with the bits stuck on the plan.....and use plenty of pins. The structure will try it's best to warp!