Spread: I assume you use at level gunners between 90-100. Having a shotgun spread isn't special. Spread will get tighter, the higher your gunners are. And no, putting on 300vets does NOT improve your spread, since the acc cap rises with each level (higher reachable cap => better spread), so all the true ability above the cap IS useless and won't be calculated in your spread. For the moment you have to accept how it is, or buy 110+ gunners.
I also assume you use reload classed gunners. They will reach acc cap at some point with enough vets and boost. If you use acc gunners, what i wrote above is your answer.
Range: Except L2 all UK bbs in the different tiers tend to have lower or the lowest ranges of all nations. The L1 91 x3 set has the lowest bb4 range i.e. To compensate this, it packs quite a punch plus the abillity to AW (which I for myself consider as the worst option offered in this game, but who cares).
L1 isn't a ship to drive line in GB - people will farm you with BB3 if played correct. L1 strength is to push in, shoot 1-2 salvos and retreat. For this it has great speed without AW, reaching 42, or even 44 if you skip most bulge.
If you want range as Uk BB4, you should choose the vanguard. Also fast (42), good damage output and way longer range, solid slingshot setup - much more viable for line usage, yet no rush in-out ship like L1.