Looks like you just got a vignette in a box.You should be able to just paint and assemble ang get decent results. Find a suitable sized wooden base, stain and seal it ans attached the finished vignette to it. If you want to elaborate the scene, do some research on Culloden. What was the terrrain like? Trees open field? If wooded, get some ground litter form Hudson and Allen and maybe a bayardi dead tree. If grassy, use some static grass, fine turf from Woodland Scenics with some of their long grass mixed in. Did the British maintain battle lines or was there a melee? Was artilery used and did the Scots advance on it? If so, consider finding an appropriate filed piece. Consider adding additonal figures from the battle as long as they fit the scene, i.e., no one standing at attention or pointing off into the distance. One thing to consider, though. Pegaso has a large 54mm compared to other companies. Another thing, this looks to be pretty old Pegaso and you may find the figures to be somewhat flatly cast compared to their more recent offerings.
The Red Lancer (http://www.redlancers.com) has a good sellection of 54 mm Culloden related figures. Go to their site and search for Culloden.