Labs are not always that easy to train and can be heavy on the lead. Whilst not a naturally snappy dog, they are very greedy so woe betide you come between a lab and his food. The problem you have is that they can knock children over with their exuberance.
Having said all that, I have had my lab for nearly twelve years. She came from a reputable breeder and had eye tests, hip scores. She has never been ill. She is also a kind, happy and beautiful dog, affectionate and loving.
She has also been absolutely infuriating, has run off and been found in nearby villages and even begging outside the local pie shop. She has hitched lifts with people in cars, but always returns. As she has got older, this has stopped although she is still known to visit the large, stately looking house nearby taking up residence in their kitchen.
She is also crapper of the century. She casts twice a year and you could knit jumpers with it.
Having said that, I absolutely hated the way she barged back into the house to get to her food bowl often knocking the kids flying. She has been taught to sit at the door, then sit again before going into the kitchen. I was told I could never train a choc lab and I am certainly no expert but yes you can.
I would buy from a good local breeder. Another way forward rather than a rescue is that the breeder I bought from sometimes lets his older bitches go to good, reliable homes. I was asked if I would be interested in a four year old who had had a terrible labour and her pups died. I had to sign never to breed from her, which he knew I wouldn't in any event. I know who took her and she is just lovely. Just ask.