I'm brewing my first batch in ten years, so essentially starting over as a home brewer. My batch (Scotch Ale) has been fermenting for 8 days now. The hydrometer reading has been stable at 1018 for two straight days, however, the air lock is still bubling, albeit very slowly. Is it too soon to add fining gelatin, or should I wait another day or two? Any help/suggestions would be great. Thanks! Mike.

If the airlock is still bubbling, I'd leave it alone for a little while longer. As long as the yeast are active, it'd be a mistake to tamper with beer at this point.
I'd recommend leaving it alone for about another week, and then add your finings. This way, the yeast have time to finish fermenting the beer fully, and it'll give them a bit of time to absorb any diacetyl that may have occurred during fermentation. Diacetyl will give your beer a buttery flavor, and you want your yeasties to eat as much of this as they can, to keep it out of your beer.

Cheers
Dave