Refills for butane gas bottles

As I live permanently in Spain my motorhome is of Spanish origin and heating and cooking uses butane gas in bottles which are swapped, not refilled.  Also the connection between van and bottle is different. I've just spent about 3 very cold weeks in England and used rather more gas than I thought I would, which set me wondering what I could do if I ran out.  I've left the van in storage in SE England until I use  it again in July/August, so I can't pack a spare bottle in my suitcase when I fly back! 

Has anyone any info about butane gas refills etc.?