We currently shoot down £400 drones with million pound rockets.
The most cost effective weapon against drones we have is the gerphard which went out of production in the 90s.
We need a vehicle mounted cannon capable of destroying drones, otherwise a wise enemy could wreck anti air defence munitions stocks by flooding a target area with lightweight drones, then send a couple of cruise missiles once the air defence is depleted increasing its chances of getting through.
The polish have a 50 cal mounted on a trailer with tracking capabilities.
At the end of 2021, the Polish Air Force tested an air defense system at its Central Range, designed specifically to counter small enemy UAVs and micro-drones.
bulgarianmilitary.com
Something a bit smaller in 7.62mm mounted on the back of a armoured vehicle or a 6 wheeler to act as convoy protection or deployable off a trailer similar to the old rapier system
Or we start producing gephards again