I've had hearing aids for 30 years now. The quality of the earmould (if there is one) and the programming is much more important than the make of aid, so you're better off using the NHS but bear in mind you may need to go back a couple times if it turns out the aid is uncomfortable or certain noises trigger feedback screeching.
Tiny in the ear aids aren't great and are only for people who are embarrassed to have aids and won't be persuaded to have anything bigger. Trust me, people really do not notice typical behind the ear aids and if they do, usually assume they are earphones...
If you have a standard 'age related' loss, ie there's a slope and the high frequencies are what is lost, then the service at Boots /Specsavers should be adequate as its what they do every day. In some areas they only do that (sometimes only for over 60s). If however you have a more unusual hearing loss like mostly middle frequencies (cookie-bite loss) then I'd go to a hospital audiology unit - they may send you anyway.
You should be able to choose the colour of aid and earmould (some aids now come open-fit, which means just a tube going into your ear canal), but often staff don't offer as too many embarrassed elderly want beige (personally, I'd go for black as it looks like tech and the silver is only paint and wears off), so ask.
You'll probably have an appt to decide what sort of aid would suit and then one to set it up, and then a review after you've used it for a few weeks. Some switch automatically between programs, most now don't have off switches so you have to open the battery a bit. Apparently people who have had aids for decades demand much more control over their tech and are pains in the arse for audiologists!
The quality of amplification is so much better than 20 years ago. Definitely get aids if recommended as if you stop hearing noises for too long, your brain will forget how to decode them - big problem with above mentioned embarrassed elderly who refuse aids for years then finally get them and they aren't much help....