You do find some birds in particular parts of the country but most of the birds I see in my garden you'd find anywhere - blue tits, great tits, sparrows, robins etc.
I don't think the seed matters too much but I don't buy sunflower seeds in their shells (husks?) because the birds drop them all over the garden and it makes a mess. That said, I think birds like sunflower seeds best - they seem to be appreciated by lots of different species, anyway. At the moment I have a 'no grow' variety which I bought at The Range. If you don't buy something like that you can find all kinds of strange plants growing under your bird feeders. Goldfinches like Niger seed but you need a special feeder for it. It's probably worth seeing if there are any goldfinches around before you buy it.
I'lll go for the sunflower seeds without their husks then, sounds like the most sensible option. Thinking of buying a bird bath, too. Will be nice just to see birds in the garden, rather than just flying over it
I grew up in the foothills of the Pennines. We had blue tits, great tits, dunnocks, wrens, sparrows, blackbirds and starlings. We just fed them peanuts, mainly because that's all that was available in those days. No squirrels though so we didn't have to worry about them getting pinched.