Hi Nic,
Some on the forum say you can disconnect the airbag without disconnecting the battery but if you turn the ignition on with it disconnected it will log an Airbag fault and the warning light will illuminate. Personally, I wouldn't want to risk the Airbag going off or causing faults. I'm in the same boat, got to do the Heater Core o rings which involves a fair bit of dash stripping. Last time I disconnected the battery I had hells own game to get the keys to re- synch, dispite mine being a later model with so called friendly re-synch but, I would rather that than chancing any other problems. It only takes an accidental short to earth and god knows what problems will manifest themselves.