Eating on my own is what I am not looking forward to - it always looks a bit strange when a woman is on her own in a pub.
It can seem a little strange sometimes (probably for men and women), but because I tend to like walking on my own, I do it all the time - and I suspect a lot of people on this site do as well (although I'm male not female). Various thoughts/suggestions:
a) if you want company - as Harland has suggested - making it obvious that you are a walker will often get you the attention of other walkers - although that may or may not be the best thing
b) if you stop at YHA's, you're very likely to come across fellow walkers with whom you can go to the pub (if you want to)
c) if you don't particularly want company or the particular company on offer - I tend to make make sure I have a good book to read
d) and if all that fails, although I regret this sounds a bit sad - I reassure myself by looking at the couples eating in the place - who generally haven't got anything to say to each other. I'd much rather be on my own with a good book than be alone with someone who I haven't got anything to say.