
I would concentrate on Obedience classes in the meantime as to start agility you do need a good level of basic obedience.
Some will take younger dogs, but they shouldn't do jumps until the bones are fully calcified, and I would say that I would want them hip scored before embarking on agility to know how good the hips are to tailor training and work accordingly.
Do you know Debbie Deuchar who does agility with her Mum's Elkhounds and Buhunds, they are not in Kent, but are in the south.