Calor are the most commonly used gas bottles in the UK.
They do butane in a blue bottle and propane in a red.
I honestly wouldnt bother using any other gas bottle than Calor as it is supplied nationwide at almost all gas suppliers shops.
Also, if you need to change the size of bottle or swap propane for butane, or visa versa, you will need your original refill agreement you will have been given when you bought your bottle.
Without the agreement, you can only change the bottle for the same size, and can't change colour bottle.