Tesco does sell a very small selection of loose teas, but, of course, you can order it on line from various places such as Whittards and get it through the post.
George, your palate has obviously been wrecked by Turkish coffee! There is a world of difference between the taste of loose tea and that of bags. It's not just quaintness.
I don't know why everyone is on about ease and convenience in regard to tea bags, I don't find them any easier than loose tea. I have a Whittard's small tea-pot with filter so that I don't need a strainer and to put a spoonful of tea into that is no more difficult or inconvenient than putting a tea bag in a cup and the result is soooooo much nicer.
Strangely, I only have the tiniest drop of milk in my tea...less than will cover the bottom of my pint mug, probably less than a teaspoonful. You'd think I could do without, but that tiny little bit of milk makes all the difference to the taste. Don't know why.
Don't drink coffee...or only very rarely. Too much gives me a headache. If I do drink it it has to be made with all milk instead of water. (This is instant coffee of course)
Instant tea is worse than teabags. It produces 'a liquid almost, but not quite entirely unlike tea'.