^ Thanks all for your feedback, always appreciated.
Looking on the web for a FZS400 panel... as rare as hens teeth to get hold of!
Although if its exactly the same dimensions/size as the bigger FZS600 rear fairing? Will keep a look out...
Do currently have rubber grommets in each hole. Seals them nicely actually plus serves the purpose, however with the aim of a perfectly smoothed fairing (with no trace of the holes), a permanent "repair" is going to be the preferred solution. Alot of effort, plus if I don't paint the fairing after the holes are gone, am planning to have the fairing vinyl wrapped (along with some other parts of the bike).
celticdog's post below is how I think I'll tackle this. Materials will be cheap, just takes some patience!...
big boy flexible filler- glue a piece of smooth plastic to the inside of the holes then cover them up with filler.
Sand the whole panel with wet and dry paper. If your careful enough you'll be left with a smooth finish for spray painting