Although faction design is a great concept forcing one play style in faction is not as OKW have proven. Eventually UKF will have to be redesigned as OKW have. Here my suggestion as to how:
Give players a series of choice. This can be implemented by the current Hammer Anvil system but making have a bigger impact on the faction design.
A) There is a Hammer Anvil choice for each building.
Reason : Makes faction more flexible and allows more tools to balance units.
IS start we no bonus or penalties their weapons work as normal about gren k98 level. They can not built trenches or sandbags.
Cost down to 260-270
Vickers get vet 1 ability timed that allow it to pack and unpack faster.
Ro.E. get also Enfield cost up 240. Mine sweepers and weapon upgrade are mutual exclusive.
Player can chose hammer on anvil for T0 for little or no cost (maybe subtract cost from other upgrade like grenades weapons and 5 man).
Choosing Hammer increase squad size to 5, infantries get armor 1.1. Ro.E. can now replace their weapon Enflieds with stens (unit upgrade).
Choosing Anvil no longer allows 5 men squads.
Reason: the defensive role of infantries and their LMG upgrades requires them to be more fragile.
Allows sandbags for both IS and Ro.E., all Enfields are replaced by scoped ones (assuming the drop rate issue is fixed) that work as current ones (worse on the move with benefits in cover), infantries get the bonuses in cover. Vecikers has the vet ability replaced by the current one.
Mortars pits start with 1 mortar pop X1.5, do not have brace range 80 cost 300.
Unlocks weapon racks with Brens and Piats. Bren is no longer a LMG but closer to bar. IS can be upgraded with pyrotechnics that allows them to drops smoke From the 25p but no explosives and get increased sight by 5 cost reduced to 20. Healing not available to IS can upgrade to base Forward assembly.
Reasons: Being able to heal in the front line allow for aggressive/defensive play, this gives the reason to return to base.
Unlocks AEC. Mortar pit has range increase to 100 and barrage range 120-130, reduced fire rate, can now fire smoke. Can be garrisoned by HMGs.
Reason: The mortar pit is there to support attack not deal damage with autofire.
Unlocks weapons racks with Vickers K and Piats. Vicker use the LMG profile.
Emplacements have pop back to normal pop can now brace. Unlocks bofors. Bofors sight increased to 45, barrage range down to 60. Mortar Pits now work as current ones with range down to 100 upgrade cost 100.
IS can be upgraded with healing so they can stay and defend for longer. Forward assembly can call in HE artillery barrages up to range 100 barrage becomes more effective maybe add suppression.
Forward assembly has its defensive role established.
Cromwell has speed reduced to 5.5 and size increased to 22. Centaur has speed increase to 5 size increase to 22.
Unlocks commanders for Tanks increase speed of tanks and reduces size. Unlocks Firefly or Tulips for Firefly.
Reasons: Hammer tanks follow cruise doctrine less armor, more speed and agility.
Unlocks 17p which cost less fuel and has less pop (maybe mutual exclusive with firefly for sure no Tulips). No tank commanders available. Tanks get more armor maybe more HP. Tanks now provide an aura that gives infantry that removes cover penalties but make them move a bit slower (they do not get cover bonus but their weapon work as if in cover when close to tanks)
Anvil tanks follow the infantry support doctrine. They support and are supported by the infantry.
Unlocks Comet. Comet smoke range is reduced to 40.
Ro.E. armor to 1.5.
Unlocks Churchill. Churchill now can provide an aura giving light cover to infantries but moves slower.
Heavy sapper: Squad with sweeper repair faster and gain veterancy for repairing building. Ro.E. can now upgrade with 5 member.
No moving penalties.
This are all direction and specifics might need some tweaking the point though is direction. The direction is creating to 2 different play styles and any mixture between them. One defensive with infantry good at defense, emplacements and slow moving tanks that support and are support by infantries. One offensive with infantries that can fight on the move, weaker emplacements and highly mobile tanks. But also allow player to chose the tools they think will help them achieve victory.
In addition more tool become available for better balancing units since emplacement for instance will be become tougher only with a trade off.
This change can be applied to other faction also. Instead of watering down the difference of the faction one can keep them but allow player to chose some of the strength and weakness.
For instance instead of having USF with strong infantry and non cost efficient support weapons one could give the player the choice to weaker infantry but better support weapons or stronger infantry but weaker support weapons.