Shame that you are so far away as im in the trade....
...A lot of traders policies will have glass cover - I would double check with the insurance company, it is also possible to add glass cover to some policies.
I think 5.15 is a better time from Swindon as the roadworks on the A420 have moved to the turnofff at Shrivenham - temporary traffic lights are slow to change and there is no quick way around.