Concur with everything Rolebama said. Penalty for driving without insurance: "6–8 penalty points plus a fine, although in certain circumstances, an instant ban will be imposed. The fine, which is means tested, can be up to £5,000."
You do have mitigation though if your company didn't tell you they'd cancelled it, obviously you had no idea and (I hope) would never have got behind the wheel if you'd known you were uninsured. Sadly these cases have been known to occur, as you can see from other similar posts. It is absolutely unacceptable that an insurance company can cancel a client's policy without telling them, leaving them to be severely punished through no fault of their own. If that happened to me I would sue the insurance company for in essence deliberately turning me into a serious motoring criminal for no reason and without telling me.
I hope the court is understanding and it goes OK for you.