Yes, it is very important, also, it will come with a JST-XH balance board, though others are available.
Oh, and yes it is available in the UK. It's just a
lot cheaper abroad.
Intellect cells use JST-XH (I'm pretty sure), and to use that in the end of the charger, just put one balance plug in the '2S' port, and one in the '3S' port (which may require a little trimming of the balance connector). It has the +ve and -ve ends marked, so match the wires to that.
This will work, but is not perhaps ideal.
Alternatively, get one of
these and two of
these, and solder up a harness following
this guide (just follow use the drop-down box and select 2s + 2s: Lipo with typical connector).