I've got three dogs - all lab/ retriever types and they are all well behaved and well socialised. However, after reading a MN dog thread I always get worried about taking them out (we walk them all without a lead in areas that they know) for fear of bumping into some of the hysterical types that these threads attract.
My dogs are not interested in you, your kids or your dogs. They are only interested in their own family: my kids, my DH, my step children and me. None of them ever set foot in a training class either
It makes no sense to be worried about bumping into hysterical people who don't want strange dogs running and jumping at them etc when your dog doesn't do that. Majority of posters have said they don't like dogs running and jumping at themselves and/or their dc, esp when the owner cant/won't control it..
Our previous lab sounds similar to yours, would walk at heel off lead, would show no interest in anybody else, obeyed all of the time once out of puppyhood, no training classes either. We currently have a 14 week old black lab puppy and if she turns out half as well behaved as our last one I'll be proper happy. Don't be worried and enjoy your dog walking.
OP, can you clarify what type of lead you've bought? Just that a retractable line is different to a training line, a training line placed loose on the floor and gives more freedom, whereas those daft retractable ones are held in the hand and don't really offer that much extra scope than a regular leader as the extra length just tangles around people's legs. It's a training line pictured below you want.