I too use HSBC and cover is for £2m treatment and public. Beware that the standard policy will only cover you for full time employees. Part time and occasional workers are an add on.
Remember, if you employ someone, even to do the pre-vac or fetch a bucket of water, no matter who and whether you pay them or not, even for 1 minute per year, then they are employees of some description. So you are legally obliged to have Employers Liability. BIG trouble if you don't.
Safe and happy insuring:)
Ken