Have had HA's for close on 25 years - always via NHS. And all batteries have always been given out for free.
My first one was just one ear and a large box type thing. Could not get on with that, Since about 20 years go, had smaller ones provided for both ears. when I moved from London, to Weston super Mare, i was surprised that I was sent to local Specsavers for audiology.
Despite my original fears that they would try to persuade me to go 'private'. they have been excellent. Have the same audiologist as those who are going private, and, as far as I can make out, not much difference in the aids I get.
Yes, every time I get new Aids, I now it will take my brain a good fortnight at least, to get used to them and noises sound very loud. But once my brain has caught up, things are pretty good.
Hearing Aids do NOT give you back perfect hearing, they just make speech, etc more understandable. Serious hearing loss is very isolating. My HA's do not work well in a very noisy place, and I have just had to accept that.
Mine go in as I get up in the morning and stay until I go to bed. I do check a lot that they are still in place, as if pulled out accidently and lost, I have to pay for a replacement. Always ae them whilst I am getting dressed and undressed for any reason. Specs need to put over them and pressed down firmly on them. Putting on/taking off coats, scarves, etc can disturb them, so learn to check that they are still in place each time you do this (only takes seconds)
So grateful that we have the NHS and they provide these, and the batteries, and any re-adjustments and replacements of the little tubes without me having to worry about whether or not I can afford it. Annoys me people who get their NHS Aids, and then do not use them. Not sure who they think they are kidding.