For this sort of legal interpretation stuff you'd do better looking at Approved Document P for advice than here. The switch exemption you crave only applies to lighting circuits.
Sounds like an expensive proposition and I doubt you could fool anybody with half a brain that it was done pre Part-P so put in a building notice and hire the test kit and do it yourself. It's not rocket science and will let you flog your house without complication when the time comes. Or buy test kit off ebay, use it, put it back on again. Make sure has current certificate.
The reference book you need for the wiring / testing etc is The On Site Guide (ISBN 184919287) but that will not cover the automation, just the 'standard' electrics.
