Thanks very much all this was exactly what I was after but couldn't think of a way of achieving it. So, just so I can apply the various comments to my situation is this correct?

1. I have wired all my sockets up using 568B so sounds like at the face plate, when I need to have a phone line I just need the RJ45 to BT adapter Steph (sorry can't see full name) suggests above
2. I wire all faceplate sockets (including those that will be phones) to the patch panels
3. I wire the cat 6 cable that is wired into my master socket into the patch panel directly rather than to another BT socket
4. Set up 3 ports on the patch panel wired in parallel (i.e. punch a long wire connecting all same colours together - e.g. same brown wire punched into brown of all 3 ports). 1 for the master and one each for the 2 phones we have
5. Patch whichever face plate ports I want to activate as a phone to one of the ports set up in set (4).

Would this work?

thanks

Lee.