In the end we had to go with BG since there were no offers on here, and the bloke who visited (who has an LPG ticket which one of the hobs uses) pointed out several things that needs correcting - such as easily accessible isolation valves behind adjacent drawers rather than at ground level behind kick boards, proper ventilation etc.
Bit of a pity that the RGI who installed the hobs last year and gave us our ticket didn't mention the AR and NCS things at the time, but that's life.
I think this BG fellow may haved been using a little ( lot ) of poetic licence in advising you!
My understanding was that the gas isolation tap on a hob merely had to be "accessible" and NOT readily accessible.
I lost an argument with RGIs that an isolation valve BEHIND a screwed in oven was not acceptable. It turns out that it IS quite acceptable. Based on that your valve behind the kickboard which can be accessed without tools seems totally acceptable.
Ventilation is well set out and depends on the size of the kitchen. In most cases, all that is required is an openable window or door!
Tony