Some great people run these fun agility classes in north London: http://www.alphadogtrainingschool.co.uk/
Did you find a class Bee? I'm also looking for a good one, so if anyone has any more recommendations I'd really like to hear them!
Vicky gave me details above for Alpha Dog Training above but it looks as though you have to sign up for eight classes. I have just left them a message to see if they do "taster" classes. I'll let you know once I hear from them.
I'm sure you can go without your dog to observe and ask questions before signing up :)
I spoke to Siobhan at Alpha Dog Training who suggested a few sessions of obedience before introducing my dog to agility. She was extremely helpful.
National Animal Welfare Trust are holding their Spring Open Day at their Hertfordshire Centre on Bank Holiday Monday 1st May.
Pop down with all the family 2 and 4 legs for a day packed with fun. Lots of different stalls and something for everyone to do, including a fun dog show and try your paw at agility at Have a Go Agility.