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Effectively it is one cable that runs in from the street, albeit that the phone wires are actually separate from the co-axial that servers the TV and Broadband.
Normally there will be a small termination box on the outside of the house. From there the phone line wire is run to a master socket. You can then run your extensions to that. Also from the termination box, the coaxial wire(s) are run to the locations that you want your TV and broadband. Depending on the layout of your house, and where you want the kit, they may run one wire to an internal junction box / isolator and split it from there, or alternatively separate wires to the separate locations.
Wires run internally can pass through walls, and are usually surface clipped to skirtings. Virgin Media installers will not enter roofspaces or drill holes in ceilings, not will they start lifting floorboards. Safety issues, and difficulty in knowing what they might be drilling into. Offering tea or coffee usually gets more co-operation and friendliness
However if your garden is a bit muddy, don't be surprised if the installer accidentially tramples a bit of this inside.
Don't rely on sky cable being of the same quality as that for Virgin Media. The wrong cable resistance or sheilding, together with poor electromechanical joints will degrade your service.
As for watching in different rooms, you either need to subscribe to a cable Set Top Box in each room, or look at some arrangement to distribute the outputted signal from you single STB to the other rooms. You can do that using ordinary aerial co-axial connected tot he STB's output RF, or there are alternative scart based video senders (you need to ensure the model you get will work with the cable STB, many are not always compatible).