Fixed this, well, kind of. Here's a quick rundown of what I did, for people like me who are struggling with connection problems.
I thought I had tried everything, was going to dump the whole thing and then remembered that I'd fixed some previous USB problems (sound card) by doing a clean boot.
First, remove Kies.
The only other thing that is required are the samsung mobile drivers from their website. I tried with and without and this would only work with them installed.
Restart your tablet, make sure MTP is selected.
You can find out how to do a clean boot for you version of windows here.
Leave your device connected via USB cable. Once you have clean booted into windows, windows will attempt to install the drivers from windows update, let it do this. It can take a minute or two to complete. You should then see a green tick in the notification area rather than the dreaded red cross.
If, for some reason, the driver doesn't install first time, you can unplug and then plug back in the USB cable and this should do the trick.
What I did find, is that the connection wasn't consistent, I could restart either my laptop or tablet and then it wouldn't connect, so I'd have to go through the above process again to get it to connect.
Doing this allowed me to flash the Clockworkmod recovery with odin 3.09, but for whatever reason, I was still unable to use the recommended Eimdall suite to flash cyanogenmod.
In the end, I downloaded the CM11 zip file to my tablet (via http) and then used ES file manager to move it to the SDCard root and then clockworkmod picked it up from there.
Also, once CM was installed, there were no connection problems at all, as far as I can see.
Hopefully this will help others in the same predicament.