Yes it is safe. It is all I have ever used and I have never had any problems.
Buying about 120.00 pounds worth per week at the moment!
Look for a small (possibly off the beaten track) garage, old school type. They generally still have it on the forecourt. I buy mine from one such place, in my local town - but then all of my local town is something that is still 19th century!!
Ask a farmer where they get theirs from - probably delivered straight to the farm???
You can get it delivered but you need somewhere to keep it, they pump it into an IBC etc and then you 'decant' it from there.
I say it every year - In the winter I will get some delivered, about 75 pence per litre for the 1000 litres. Hven't done it yet!!!
Rob