totally agree, you would not benefit from a full course as you have done a lot of flying already and used depower so know how to use the harness and understand how the kite works.
with some private tuition you would be able to get into the water pretty soon and progress at your own pace.
kitewise perfect, 12 and 8/9 give you a huge range and you can go out in anything apart from storms
have a look at all sorts of brands, flexi are not the best for sure. if you want the kite to be a little more fun and better for buggy jumping then the ion will be better than the atom. other brands to look at are slingshot, naish, takoon, liquid force.....loads! Try some out if possible
most guys from london head to hayling, witterings, brighton area, camber/greastone, poole, mostly south coast, or you can head to south wales