Firstly if your not confident in doing it Luke, get someone qualified to do it for you.
The boys at PLANET will do it or contact Hpac.
All the bottles I have done HAVEN'T had Loctite on but according to some threads on this forum, some do.
I put the bottle in a soft jawed vice MAKING SURE IT IS COMPLETELY EMPTY!!! and use some Knippex pliers to unscrew the reg. If you dont have Knippex tools wrap the reg in a cloth and use normal grips. The cloth stops you chewing the reg up. It should come off easy enough as it is normally an O ring on the reg that seals it.
Hope this helps, but remember SAFETY FIRST!!!!!
Nige