Switching to Cable

I'm currently with orange, if I switch to Virgin Cable do I still need to obtain a MAC Code

No. A MAC code is for changing the ISP down 1 set of wires.

Thanks

MAC codes are all about service continuity, but as cable broadband is independent of phone broadband it's down to you to manage the continuity. Most people get the new broadband up and working before ceasing the old to ensure that there's no gap.

How about keeping the phone line broadbad and getting cable broadband then bridging both connections.

What does bridging both connections mean? and how is this done?

running two WAN connections at once is possible but from your questions its probably not for you.