I've been riding, teaching, competing and training horses for about 22 years now.  IM me if you need info.

My advice is to take the 8 week course.  Before you sign up, though, I would go watch a lesson.  Make sure the instructor appears to be competent, emphasizes safety, that the classes aren't too large (3 riders MAX), that they keep their equipment in good shape (no dirty leather, seams coming apart) and that the horses are well mannered and in good condition.

An active barn is the best place to ride because it is more fun and more motivating to ride when you see other people around doing it, too.  

Word of caution: an active barn means LOTS of horse people and EVERY horse person does it differently and will VOLUNTEER to tell you how you are doing things wrong.  Listen to your instructor.  Unless you ask for advice or the person appears to be genuinely competent and you feel they are a good person to learn from, politely tell them that you are a beginner and it's too confusing to learn everything at once and that you are trying to concentrate on what your instructor says.  Say thank you and go on about your business.  

Do not rush into purchasing a horse.  I would recommend taking lessons for at least six months to a year to make sure this is something you genuinely want to do.  Lease a horse before you buy.  And if you do decide to buy, board them at an active barn that you enjoy going out to... otherwise this will be another drain on your wallet that you will resent.

Again.. lessons for a long time.  Even top level riders realize that they will never be done taking lessons.  You will always be learning.  And $20-40 a week for a lesson is a lot cheaper than the $150-350 you'll be paying to board a horse at a decent facility.

If you DO decide to buy a horse... have your trainer help you look and match you with a horse.  Don't go for the youngest horse because you somehow think a younger horse is worth more.  An older horse 10-16 years of age still has plenty of spunk but has enough miles on them to be level headed and know their job.  THAT is a horse that will be enjoyed.  Trust me.... you'll laugh the first time you see some idiot trying to ride a greenbroke three year old on the trail who has decided that the boogey man is around every corner and they can get a better view from their back legs followed quickly by a retreat at 120 miles an hour.