Grame confused by "do they tell you what distance they need to be from walls etc?" - who would need to tell this to a Ff, after all it is the other way round, surely? It is our job to know this! Any Ff who doesn't should not be in the job, unless they are still in training of course. It is a requirement of a Competent firefighter to have the knowledge and understanding for the NOS and just take a peek at Unit 1.
Andy - Is it not that it is the preferred method becuase it avoids having to put up a ladder inside someones nice clean hall/landing, rather than not to put up/climb a ladder per se? We have small step boxes for that reason. FRS ladders are not really designed for clean internal work. MAybe specific CS step ladders would be an answer, but seems that your FRS has made a sensible choice.
I reckon they saw you coming on the screws too, after all alarms come with two free!