Sorry, I'm not offended in any way! It's my fault as I have been trying to cut down on the length of my posts - obviously cut them a bit too far!! Also, I quite often sound like a complete cow but I am trying not mooo, I mean to!

If this lady was talking about extending leads then I do agree with her - I hate them with a passion (see there I go again! Loads of people use them and love them so sorry in advance to all of you!).
I would suggest holding off the training class until you have more confidence and control. The dog is going to be a hundred times more distracted in a room full of other dogs and people.
Going back to basics is the way to do it. Try each excersise in the living room first until the dog is 100% with it. Then move to the garden, first on the lead and then on the long line and eventually off lead.
Have a go at varying the rewards you give, go loopy when the dog does something right. Big fuss, silly voice, jump around (another reason for staying indoors to start with!!!) and throw a Kong or tennis ball as the final bit of the reward. You need to find a reaction that the dog loves so much he will try anything to get you to do it again.
When out in the garden occasionally call his name. If he looks at you go into the loopy routine and encourage him to come to you before you throw the toy or give him a treat. He will realise it is in his own best interest to pay attention to you.
Good luck, hope this helps and I'm sorry I came across as stroppy!