Hi everyone, I just thought I would post to say that I found a great Agility place near me in the end that takes puppies for beginner classes from 5 months.
So if anyone else was looking for something in the area I would strongly recommend them. The club is called Millbrook Agility Dogs:
http://www.madkathagility.com/Maggie is now 7 1/2 months old and we have enrolled her on a 15 week course (although they range from 5 & 10 to 15 weeks), which will take her up to the age where she can start doing the equipment raised off the floor.
I spoke with the owner, Kathri Tasker, who is great and all her trainers are very experienced and train using motivational and reward-based methods.
The venues are really nice (they have 2 local to me - one indoors, one outdoors) and we had great fun.
Now all I have to do is try and get Maggie to calm down and pay attention to me in class instead of everything and everyone else! :-)