Sorry for the late reply, kept meaning to post but I kept forgetting. Anyway, here's a great recreation of French uniform from the French-Indian War, and there's a detailed full-body image here and here. Of course there'd be some variation among different regiments, they may have a red trim like so, but for the most part that's your average French infantryman would look like at the time and place.

As for the British, here's an example of a grenadier from the 1750s, here's another example of uniforms from the time here as well.

Hope that helped some!