They are a nice bit of kit, clean light, see how much gas you have and I have found a lot of places especially garden centres in SE London sell them, although I'm still on my first 10kg bottle, even after 4 weeks in France. The BP Gaslight web page has a link to Truma for the pigtails required.
Yes the garden centres in SE London are fine for getting refill - but I steer clear of SE London when I go caravanning! Try running out in mid -Wales or parts of the Lake District.