We have a 30 ltr underslung tank and we fill at a place in Northampton. The pump is used by a few motorhomes and you just pull up, fill and pay. Westbridge Motors. No it is not the cheapest, but as has already been said, it isn't worth the hassle wondering if you are going to get refused. But that one fill will last us until our month in France in Sep0tember. So we will fill before we go.