I did the parent centre ones. My MW told me to stay clear of the free ones at the hospital as they often attract a lower class of people IYGWIM. A friend did her's there and she didn't get a coffee group out of it and didn't get along with any of the people. Whereas, we still catch up at least once a week for various outings and we all get along really well.
As far as the learning side of it goes, I learnt far more from reading this forum and books.