I’m embarrassed to go in a shop to buy woman’s leggings

You specified 'woman's leggings.' If you don't think you look like the demographic for buying them, the majority of people will assume you are buying them for someone else. You don't have to answer to anyone, just act like you own the place. Good luck!

Don't worry to much its probably the only time you will ever see the person. So just go in buy them and be glad you won't see them again it helps for me. :)

Not got1

I saw some tights on offer in a supermarket a couple of weeks ago, considered texting gf to see if she wanted them then realised she was busy and wouldn't respond in time. It didn't even cross my mind that anyone might make any sort of judgement on me buying them. I guess if you're buying with confidence no one would think they were for you, or care if they did, and the basket full of other stuff would probably make it even less likely that anyone even noticed them.