I grew enough lavender plants from seed to make a hedge along the path to my back door about 10 years ago and it was quite a success. But we had a number of hot dry summers back then so, even in heavy clay, the odds were in my favour. The summer just gone could not have been worse for Mediterranean plants, I'm afraid. For lavender, good drainage is everything, both for propagation and for existing plants. I don't have a garden to speak of since moving earlier in the year and, much as I miss the garden I created and loved and left behind, at least there isn't the worry, disappointment and hard work now. My old house has been empty since I moved out and I suspect there won't be much left of my lavender hedge!
Interestingly, I miss even more my airing cupboard (my linen cupboard, as I rather grandly used to call it). I hadn't realised that modern houses don't have them! I used to tuck lavender bags into the piles of bedlinen and towels and the warmth from the hot water tank did the rest. Now I have to keep spare linen in drawers under the beds the effect isn't the same. Hey ho, life is simpler now - I must remember that!