Re: Easy peezy, lemon squeezy
>Just need to decide how much future-proofing I need - 6a worth the extra at the mo?
Yes, I would go with Cat6a, although buy it by the roll rather than as pre-terminated lengths.
Need to be careful about Cat6a patch panels (if you need them), from an installers viewpoint, there are some really good ones around and some really bad ones, cost doesn't seem to be a factor.
As for future proofing, I would only cable the essentials initially and install more as and when required.
>conduit?
Yes, separate to the electricity and with capacity for a couple of additional runs. Basically, rewire in a structured way and give yourself access so you can access ceiling/under floor voids once the carpets have been laid.
Also make sure you have vertical conduit from lowest floor to attic and a power circuit (other than lights) to the attic.
If you make all your power outlets double socket, you will then be able to change them from double power to single power plus 1 or 2 data as required. Obviously, some places such as behind the TV/media centre will require additional sockets.
It will be expensive (compared to standard cabling) but enjoy the journey and the results!