Injecting yourself in a public place

I see no reason why anyone would stop you from injecting at the table. It is what I have always done.
There is a big difference between injecting in public and injecting publicly. Most of the time I do it, no one notices.

My dad injects wherever he is, into his abdomen and has never had any comments made to my knowledge. Showing a bit of skin over your abdomen surely isn’t offensive. I can’t see how anyone could legally stop you

I had a T1 colleague who injected at the table discretely, and never saw or heard anyone make a fuss. But I had a friend whose husband injected at the table and he always laid out a used a tissue with lots of old bloodstains on it (and carefully, very slowly arranged all his kit) - that tissue did make me feel queasy!

I completely understand your apprehension, and I was a bit wary of injecting in public too, but no one really notices.

Earlier today, I injected sitting on a park bench. I just did it casually and I don't think no one even noticed.

I was advised by my team to never inject in toilets since they're not sanitary. They said if a restaurant asked me not to do it at the table (but really, but they time they saw what I was doing and said something to me, I'd be done), I should ask to use somewhere like their staff room, but definitely not the toilet. Asking someone to use the toilets to inject would be like asking someone to feed a baby in the toilets.