Arizer Extreme Q does exactly the same as the Volcano at half the price, not as sturdy though.
Since you're in Wales vapefiend or vaposhop might be good places to look for a vaporizer.
If you want proper control of temperature you have to get a convection vaporizer, they're more expensive than conduction vaporizers, but zero combustion and you get better efficiency, taste and effect from your product
The strain has a lot to say in whether you get medical benefits without getting high, but in my opinion you can't really get proper pain relief without at least getting a slight buzz, but all will be far from the knock you get from morphine or tremadolhydrochloride type painkillers.