Loved reading this posting inquiring about growing lavender. I live in the Pacific NW near a little town called Sequim which is also called the lavender capital of the US due to their sunny dry climate and well drained soil. Most of our area is very wet and cloudy but not sunny Sequim, pronounced "Sqwim". They have a huge festival each summer celebrating their wonderful lavender farms.
You might try googling Lavender Festival Sequim, WA. There are lots of lavender farms here that enjoy helping people around the country learn to grow the beautiful plants. I think some of them even ship little plants also for a very reasonable price. Paying ten or twelve buck for a three gallon seems very costly. Here we see tons of little plants on sale all spring and summer at our Home Depot. Every little mom and pop store here sells two inch pots for two bucks. So I would absolutely advise you to check out ordering plants from some farm here to save a year of growing from seed.
I love doing dried flower crafting which includes rosebuds and lavender. Munstead is my favorite for the lovely dark color and ease of working with the dried flowers.
I grow my lavender plants in raised beds alongside my veggies in well drained sandy soil, no mulch. They hate water logged soil and mulch. They also dislike being transplanted beyond babyhood so make sure where you plant them. Moving a fullgrown one may spell disaster.
I also have an herb garden which has a little hedge of lavender growing around the walkways. I don't harvest that often, just let it be to scent the entire garden all summer.
Please let me know if there is anything I can do to help you realize your dream of a cottage garden look along your drive. I think it is fantastic the idea.
what Pat told you is just so right on. Excellent information!
SouthDakotaRose