Hi Greg,
I'm pretty sure an RV-10, being a homebuilt aircraft, would never be eligible for a C. of A. It would only operate under the LAA-overseen Permit To Fly regime.
There has been a change recently in the rules governing flight training in Permit aircraft (see
http://www.caa.co.uk/docs/33/ORS4_802.pdf ) but these would not help in your situation.
The document specifically states that it "excludes instruction in flying given for the purpose of becoming qualified for the grant of a pilot’s licence or the inclusion or variation of any rating or qualification in a pilot’s licence."
On a separate point, the RV-10 is probably not the ideal choice of training aircraft. The RV-10 is a large aircraft with a big engine which makes it more expensive to operate.
Sorry if I'm bursting your bubble. There is much to be gained by all involved from the experience of building an aircraft. If you restrict your sights just to building an aircraft then the RV-12 would be an ideal match for that objective.
There are articles in the Van's RVator magazine about TeenFlight where Van's are working with a group of 14 - 17 year old's to build an RV-12. As an example, see page 7 here:
http://www.vansaircraft.com/RVator/2009/5-2009-RVator.pdf Best of Luck,
Steve Hutt