I see others have already told you all you need to know about pg and vg
I'm sorry to say I don't much like the site where you buy, they don't seem consistent with their data (like saying their juices go from 0% to 1.6% nic and then selling 18mg/ml; things like that just really annoy me), and they never say what pg/vg content is (which is important to know if you are allergic to pg, which some people are). Anyway, I'm not really familiar with their products so I can't judge. I suggest you find a thread (or start new one) about blu, someone here is sure to be familiar with it and can give you better advice.
But if I were you (and that's just my opinion, feel free to ignore me

) I'd look into some different devices (I already mentioned Zlide Tube, or maybe Vaporrsso kit sky solo; look for stick or pod systems, they are small and easy to use) and then you can buy whatever flavour, strength and pg/vg ratio juice you want.
The way I see it you are now limited to just one brand (I might be wrong but again, I never used this device) and that's just not ok, there's a whole world of juices out there. If you really think vaping is for you then give this at least a thought.
Most important however is to find more info about your device and find good uk site to buy from.
Ask around and don't give up