Do not become confused, BIG DAD, between the need to have third party insurance to comply with the Road Traffic Act, and your liability to compensate a third party for damage or harm you cause to them or their property.
It is mandatory to have insurance against third party risks if you intend to drive a motor vehicle on a public road or in a public place. Your company car park may fall into the definition of a public place (even though it is privately owned) depending upon who has access and how that access is controlled.
However, even if it is deemed to be a private place, you are still liable to pay compensation if you cause damage or injury through your negligence whilst there. Whether you have insurance to cover you against these risks is a matter for you and your insurers to determine. (Most insurers will cover you for such an incident, even if it did happen in a �private place�). However, lack of any such insurance does not remove the burden of compensation from you.