The amount of cover you need totally depends on your individual business and the likely risks you may encounter. It may also depend on the kind of work you do.
A minimum of £5m in Public Liability cover is standard in the construction industry. However, you may have clients who insist on a higher level before they will allow you to work with them, or work on their premises.
If you have employees, a minimum of £5m Employers Liability Cover is required by law.
The amount of cover you might need for tools, plant and other options needs some thought. It’s easy to underestimate how valuable your kit is until it has gone missing and you have the bill for replacements.