I did mine in CT125 rather than CT100. Thicker and better screened.
Consider also running a pair of cables to somewhere where you can keep a media player if you don’t want one under the tv. Run at least one HDMI cable from the media centre to each tv.
Also run speaker cable from the media centre, tv and/or stereo to speaker positions. Don’t forget surround sound speakers. I also have speakers in the kitchen, garden and bathroom. Use mains cable it’s MUCH cheaper than decent speaker cable and just as good.
+1 for cat 6 from broadband router (next to main phone socket) to tv, media centre, hifi and anywhere you might want a wireless repeater (upstairs? garden?).
Buy a decent distribution amp for audio and tv signals
Don’t bother with phone cable. You can get structured cables that contain AV, network, speakers cables in one. Many combinations are available but it’s not cheap.