Name your map : Highlands
Is your map concept specifically aimed at competitive, public play or both? Public
How are things going to play out gameplay wise? Typically, the public mindset for this map, is that the UK has to always move to attack the French because of their high ground and single cannon. This mindset comes from Siege mode. I would think a good balance to both sides would be to add 1 standard cannon on the UK and one more on the French side. It would create a better sense of urgency for the french to cross and attack the UK since the terrain on their side entirely favors the France.
There are 3-4 main areas the French can use to ambush the advancing UK whereas the UK may only have 1 tenuous defensive position at best.