Regs simply put the onus on you..and if you expect step-by-step guidance then you will get the same response as DIYers get on here...
Question: If I install cables in this location, is there a risk they might cause an obstruction in the event of fire?
Answer: Yes, they might. Thus, I will install them, to the best of my ability and with the appropriate fixings, so as to minimise that risk.
If I doubt my ability...to assess or install...then I will seek expert advice, and having sought and obtained that advice, or having assessed and made my own decision, I will record that so I may answer any questions at a later date.
If I am unhappy with that, I will not install.
This post attached by Pirate is the one I praised, it sets out what we should all do in the same circumstances. post number 60