Ok, just turn the switch to the bottom facing the floor in other words(regulator Off)), it should be on the horizontal position now (gas off). when you want gas flowing out it needs turning through 180 degrees. in other words to the sky (gas on). theres a red or grey button thingy too this needs pressing in to move the switch.
if its one with a big nut between the regulator and cylinder it unscrews the wrong way round (the spanner costs about 3 quid in camping shops)not sure of the seven k ,and the larger ones unclip rather than unscrew by turning a "lever" and pulling the regulator off.
It's easy to disconnect but if you are unsure take the lot to your calor gas centre and ask them to show you the method, once you have seen it done you will have no problems next time.
No, that's the standard fitting on a Calor 4.5 Kg bottle. Fatbloke does not need a new regulator.
But the OP has a 7 Kg bottle which has the easy on/off switch, if it's Calor. Budget Gas and all their cronies - Alta Gas, Flogas, etc - have a similar one that will fit their 7 Kg & 4.5 Kg bottles. Just twiddle the knob 90 degrees to horizontal for gas off, another 90 degrees and the regulator lifts off. If it doesn't lift off then you've turned it on so do a 180 degree turn.
------------- Caz
If you can't see the light at the end of the tunnel, just keep going till you go round the bend.