Personally I would have thought private lessons were the best way to learn. A bit like learning to drive - it's best to learn with a driving instructor, you can always get people to sit with you for practice, but you need the proper instruction.
Alternatively, you could try learning at home. Sounds daft, but my son wanted to learn the piano and our local teachers were expensive and miles away! He bought an online training package called Rocket Piano (www.learnpianotoday.info) and although I was initially skeptical, he has learned theory and technique and is now really good!