In reply to Graham Booth:
I prefer physical venues where you can taste, and converse, that have online options. It's also a big benefit to get full refunds if you don't like a wine that was recommended (let alone if a bottle is corked or otherwise off).
I find enjoyment is very loosely related to cost. I prefer big flavoured red wines with lower tanin levels and tend to buy either side of the 'ten' (in the UK pounds, in the EU Euros or in the US dollars). If budgets are tight, Lidl are not to be sniffed at (and have had some amazing bargains over the years including a ridiculous priced Canadian Eiswein); equally, if you have the money, some independent wine shops are very good.
I'd never recommend just buying random discounted wine, other than a cheaper way to try something. A top tip if you really like something is to buy as much as you can afford, as wines can change from year to year.
My current contribution to the thread from UK supermarkets would be these from Majestic.
Their Bread and Butter pinot, especially if it ever goes on sale again (I think it was reduced to £10.99)... great value for a quality pinot and almost creamy.
https://www.majestic.co.uk/wines/bread-butter-pinot-noir-18128
Plus my standard quaff which is The Guvnor, a Spanish red, very fruity with low tanins.
https://www.majestic.co.uk/wines/the-guvnor-14666
For the decade following the 2008 crash Majestic had some amazing value and selection range for Spanish reds (especially non riojas).... not a patch on a proper Spanish bodega though