Ok, so this is what I meant by different drones. I know a bit about the naval defence. To sink an undefended warship you'll need a decent sized warhead so the types of drone you are talking about, the swarm, wouldn't cut it. Effective warheads will be too big and expensive to "swarm", eg Exocet.
Our Destroyers currently have "Sea Viper" Aster 15 and 30, plus close in defence in the form of Phalanx. Our type 26 have "Sea Ceptor" which uses CAMM, plus the Phalanx.
The C&C systems can track and assess up to 255 small fast objects at once. Anything within 30km can be hit, surface vessels , aircraft, missiles or drones, including ballistic missiles (Aster30). Anything small and not worth £££ firing a missile will be drilled by Phalanx. I guess the greatest threat might be a thousand small drones going for the radar system, but small drones aren't going to have the range, for example. Going forward Dragonfire will get installed which will form part of that layered defence, it's very cheap and good for small drones but needs clear weather to be effective, so Phalanx wouldn't be replaced.