I would think a breed with a big fluffy fleece in an area hoaching with flies, especially for a first time keeper, is not a good idea.
For rare breeds of sheep, there are hill sheep, Primitives and big fluffy ones. They each have their own characteristics and points for and against - worth researching into them all.
I would say don't rush into buying sheep before you are ready, just because you are inspired today. Let the idea settle, find out all you can, then buy a handful of wethers of a breed you're interested in. Use them to keep your grass down, learn all you can about general sheep keeping from them, then send them off for slaughter. If you can't do that, then think seriously as to whether sheep breeding is right for you. Wethers can be kept for several years as grass cutters, but really if you get females then you should be breeding from them, especially of a rare breed.
In fact this question has been explored countless times on TAS, so search back over the past few years and you will find masses of relevant posts, so we don't all have to repeat ourselves.
Well done for taking the plunge and moving away from London - believe it or not I've only been there a handful of times but I hate the place (except when I cycled right across the middle, including down Oxford street at 4 in the morning - quite fun). I hope you really love your new home and whatever animals you finally decide to keep.