This page contains a series of documents containing the information you need to make contact with various national youth groups.
The links and other contact details found in the documents should allow you to drill down to make contact at a more local level.
When making contact, you should ensure you know what you are going to be offering their group for example, a tour of your tower or a session on handbells etc.
Be careful not to hard sell this as a recruitment exercise as you may be seen as being in competition with the group resulting in a negative response. The ideal aim for any engagement is to raise awareness of ringing as a fun activity.