Before messing with the method of terraforming (scripts vs. schematic brush), I'd suggest just doing the following. Compile a list of SchemSets you want to use for each "layer" of the forest - trees, undergrowth, and ground cover. For a quick example:
Trees: ForestOak, AlderM, ForestAlder, BAshM, SkinnyBAshM
Undergrowth: AllBushLow, CarcBushMix, OakBushL, ValeShrubS
Ground Cover: GroundCoverS, CarcMeadow, CarcStump
Whichever ones you choose, try to keep each layer somewhat limited (around 3-7 schems for each layer). All the schemsets can be found
here, and
DutchGuard gave a helpful list of Kingswood tree species
here. You'll want to play around with different mixes of schemsets using the schematic brush to see what mixes look good.
Probably we'll want to have custom-made schemsets for ancient oaks etc. when we get around to terraforming the main Kingswood (the large Oak schemsets we have currently are pretty outdated), but since your forest is on the outskirts of the Kingswood you shouldn't have to worry about that as much.