Stand alone insurance for the stock by itself might be tricky or expensive to set up. Although it won’t seem terribly relevant try looking at providers of public liability insurance, not for that cover in itself but lots of brokers will bundle other covers with the PL policy and for me I’ve found that cheaper than stand alone cover. I need PL insurance anyway, but adding goods/tools in transit cover to it cost buttons and the PL and other insurance together is cheaper all in than the goods/tools insurance would have been on its own.
There are a few online brokers that do that kind of bundle, I think last time it did it through Simply Business