Ok, I'm sorry, I'm asking the same question again.
Still not made my mind up which tester to go for to get used to before I start the training.
I'm put off the HT/Martindale due to the EFLI resolution of 1 ohm
The rcd auto test sounds a good idea so that seems to put out the megger...
Your assumption is correct, it also includes garages attached to the house. Basically any change which would require the person making the change, to the existing wiring, to have to ensure that the safety of the installation is not compramised.
I'm also looking at getting the HT kit, but probably going for the macrotest for the slight difference in cost.
take a look at this thread
http://www.iee.org/Forums/Forum/messageview.cfm?catid=205&threadid=7021&enterthread=y