Be careful with P/L insurance. It is true you get what you pay for. the Groupama policy (as will most cheap ones) will cover you to 4 storeys only. It will also not cover the actual pane of glass you are working on. There are many exclusions.
I just renewed mine through simply business and paid £240 but got £2500 tool and equipment cover which includes damage and theft. Also covers you for scratches to glass etc.
My advice is work out what you need to be insured for and what you anticipate needing over the forthcoming year and then look at it.