@sparklemagicsnow
I'm struggling to see any obvious pattern in your likes/dislikes bar one: the things you say you don't like are widely available in cheap/crap form, whereas the things you say are OK are generally not available at the bargain end.
A £60 bottle of Sancerre in a Michelin-starred restaurant will cost about £15 from a retailer. By happy coincidence, Aldi have one in their 'Winemaster's Lot' Christmas range for £12.99 which should be something of a bargain. While you're there check out the Pouilly-Fumé from the same range (£14.99, although they've dropped the prices by a quid or so on quite a few of them in the last week or two).
Pinot Grigio is a strange one. In Italy it tends to be quite neutral but in France (Alsace only, called Pinot Gris there) it can be steely and spicy. New World producers tend to produce something more like the Alsatian version. But bulk Pinot Grigio - often house wines in pubs where they are bottled as 'exclusive' brands that therefore cannot be benchmarked for price elsewhere - can be quite chemical and just not very good because they are virtually industrial wines. The actual wine content of a bottle of one of these can cost as little as 15p from the producer and would be used in Italy to cook with. Aldi again (sorry - I really don't work for them!) has an Alsace Pinot Gris in its Specially Selected range for £7.99 which will taste nothing like "pinot grigio" by the glass in the pub.
Chardonnay - again there's a lot of cheap nasty stuff floating around. It grows almost anywhere without too much care so volume producers care little about grape selection or quality, they throw in a load of oak chips to disguise it, and you end up with something like a vanilla fruit bomb masquerading as wine.
There are dry rosés around - mostly from Provence and elsewhere in southern France, and therefore expensive - but I agree a lot of the supermarket ones can taste like the pic'n'mix counter got loose in your mouth. Lidl have one at the moment from Portugal called Cabriz, from the Dão region, which is just off-dry but a serious food wine.
Cava is for my money much more like champagne than Prosecco is, which is why I'm struggling to see obvious patterns in your likes/dislikes. Are you definitely comparing like with like? Most champagne and cava is Brut (dry) - tart and biscuity - whereas even 'Extra Dry' Prosecco can be fruitier and sweeter.
Red is a whole other ballgame, but the syrupy, cloying stuff with names like 19 Crimes or Jammy Red Roo (there was a whole other thread about this) is not representative at all. Interesting that you found pinot noir OK - it is one of the most difficult grapes to grow and you never see a cheap one anywhere, unlike say shiraz or cabernet sauvignon. Try a red from the Douro in Portugal (available in both Lidl - Azinhaga de Ouro - and Aldi - Mimo Moutinho - for £5-6): they have concentrated fruit without the syrupy sweetness you get from some contemporary mass market New World stuff, have plenty of structure to give complexity only really found in Bordeaux at double the price, and soft tannins so as not to frighten the horses.
Rather than going on a course, you might be better off buying a book or two and then just experimenting yourself.