Wow!
Thank you all for the replies!
I still have the pickups I took out. They're Ibanez INF2s, so I could put those back in...
Not too keen on the scratchplate idea - purely from a cosmetic point of view, I just don't particularly like them. It's clear from everyone's comments that those two options are cosmetically the best to do. I don't think I'd like to attempt filling the holes if it's going to be visible anyway without a complete re-spray (and no guarantee that it will be completely fixed then, either!)
I very much doubt I'll be undoing this pickup-removal myself, but if for any reason I do decide to sell, I can always put them back, I suppose.
One option might be getting some scratchplate-type plastic and cutting it to just sit over the current holes (ie a rectangular bit). I can then use the pup screw-holes to fix it, and get the best of both worlds...
Thanks again for all the responses!
Oooh, just got a phone call, we have a gig tomorrow night! Might try to sort out something for that :)
Roo