It's also be worth knowing that some insurance deals aimed at small businesses bundle up several of the most useful/legally required types of insurance, including Employer's Liability.

For example, my contracting company took out a policy for the Professional Indemnity cover, but it also comes with some Public Liability and sufficient Employer's Liability cover to meet statutory obligations if we take on employees.

I don't know whether this works out cheaper than finding separate policies for exactly what you need, so obviously please do your homework if you're in a position of needing this type of cover.