I agree, I trained with nailzone, which was good as a foundation, but plan to re-train with CND. The good thing about the nailzone course is that you can get ILA funding for it, so £200 off the course cost, making it £150. However, unless you really throw yoursef into doing nails straight away you would probably lose confidence and forget all the training as it is only a 2 day course). In hindsight I wish I'd researched it properly and trained with CND to start with.
Good luck! Hope you find the course you are looking for.