It certainly seems to be hit and miss who will allow it, but let's put it this way...if I'm in a remote place and there's only one guaranteed place of a refill within 50 miles (let's say for argument's sake Morrisons) it would make sense to go with Safefill rather than hit the issues I had yesterday. I was calling every man and his dog that has LPG listed on their site asking if they would refill bottles and everyone said no. I may not be able to tow the 29ft trailer to a LPG refill station, or even get it in so the only option there would be to take the bottle out. If the forecourt doesn't allow it then I'd be without gas.
This is the reason we plumbed our white bottles into a locker and had the filler outside!!
When we first got our unit with the white bottles it was easy to fill them----- then everyone started filling calor etc and forecourts got very wary because a lot of LPG is supplied to garages by calor!!! They looked at it as us getting cheap gas instead of paying their rip off prices for bottles!!.
Is there any chance of having an underslung tank, then there are no problems getting it!.
You would not necessarily have to change anything if you used different bottles, we have found propane/ butane or LPG (a mixture of both) all seems to work the same!!!. Even through the US regulator. You can feed gas into your BBQ point (some are one way!) just get a local bottle and regulator, your BBQ point normally supplies low pressure so you must put low pressure into it.