Hi, don't know where to start with this post as if you are so unsure of cable types you probably shouldn't be doing it yourself!!!!!!
For infomation only; older wiring used grey or white sheath at random, new cables are grey for ordinary circuits and white is low smoke & fume cable used for safety circuits (at higher cost).
All power cables 2.5mm2 upwards for domestic wiring will be twin & Earths,
lighting 1.0/1.5 mm2 with earths may be twin or 3 core/E.
Twin Brown/Blue for looping from mains to each light, twin Brown/Brown should be used between light & switch (cheap-skates use Brown/Blue and sleeve blue with brown sleeving!).
3 Core/E goes between 2 way switches & new colours are Brn/Blk/Grey+E the blk/grey should be over sleeved brn also as all are live @ some point.
Sometimes 3Core/E used to bring Live to double sw. & grey/ blk used as sw. lives to 2 fittings but that's getting a bit far in I think for now,
see forum 'wiring lights' in full colour, also plenty DIY books on sale (unfortunately!), regards SPARX
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