Firstly, you could lay a cable from the home hub up to his room (easy, you can have them made to length up to 100m at most locally run PC shops for not much money). On the end of this cable he can either plug his laptop in directly (faster connection, cheaper) OR you can attach a standalone WAP (wireless access point).
Laying a cable like this is simple, it's only going to be a case of tucking under a few carpets and going under a few carpet grips - maybe a couple of discreet holes drilled in a couple of walls but generally anyone in your family with a bit of DIY knowledge could do this in 15mins. You could even get someone in to lay the cable, out of the way, complete with trunking and a wall connection point in your son's room, for not much money. Check the yellow pages or ask around, there are always home IT support guys desperate for work - me being one of them! You don't live in Newcastle do you...? ;)
The second option is you could use ethernet-over-power plugs. They're mains adapters, typically you get two of them, plug one in near your hub and one in where you want to extend the network to. Each will allow you to connect a network cable (one to the home hub, one to your son's laptop or a WAP as described above) and it will send the network data across your mains cables. Perfectly safe. This one would suit you very well as it has a wireless access point built into the second plug:
http://www.devolo.co.uk/uk_EN/produkte/dLAN/dl anwirelessextsk.html
In fact, either way I'd encourage you to ring your local IT guy. He'll definitely be glad of the work.