County squad is a good place to start. Dates for the Yorkshire squads, and application forms, _should_ be available from this weekend (Yorkshire champs) - as a minimum he'll have had to have had one competitive outdoor season.
Regular access to quality coaching will also be needed, contact your CCO (Kath Fitzpatrick - details on the YAA website) who'll be able to point you in the right direction.
As Trunkles said, be prepared for significant commitment, from both of you, him for the effort needed, you for the support and playing driver to all the competitions.
/realism on
As others have alluded to, a goal of shooting in the London Olympics may be unrealistic (given his age), but there is another one in 2016 (and 2020...)
/realism off