At its best in the Summer months when it's in full flower, and also when there are lots of varieties to choose from, Lavender needs to be in a free draining position where it will get as much sun as possible.
There are English varieties with the traditional flowers and these are either lower growing more compact varieties or the larger, looser growing and taller types. Then there are the French varieties which will have the tufted flowers - the little bunny rabbit ears sticking out at the end. Generally they're a little less hardy and will cope if given a sheltered site or some protection or there are varieties that won't survive the Winter. The least hardy seem to be those with flowers of two colours. And finally there are those with a more fringed leaf. So check back as we approach the warmer months when there's a large range to choose from.