If you become an NSRA individual full member, the standard insurance package includes £5,000 all risks for shooting equipment. NSRA is £83 a year, and there are intro deals if you contract for 3 years.
You can double the cover to £10,000 if you pay extra; I don't know what the premium is.
NSRA also gives you £10m civil liability £12,500 personal accident and £25,000 legal costs.
So, for your present £200 plus £83 or less you have £5k of all risks. If you took the guns out of your present cover the £200 might go down.
For £429, the word shaft comes to mind.