If you ring VM to arrange it they may be willing to supply the cable and arrange an engineer to do the actual connections if you run the cabling - explain that you need to run in an a manner that is going to take time/whilst decorating (there will almost certainly be a fee for this, I think the standard "I want to move my services to a different room" fee is about £100 now).
Do not touch the outside cabling yourself - if you do not terminate it properly, or use the wrong cable they will not be happy if/when it causes a fault that requires them to send an engineer out to fix (I think it's technically illegal for you to access the external box, certainly against their T&C as that is I believe always their property).