My mate got his first car through NHS salary sacrifice. It worked for him because he knew nothing about cars, or servicing, and also the insurance was much cheaper than outside quotes. He then paid off the rest of the car so he owned it, then sold it. It can work for some, but yes a very pricey way to do it if you're not comfortable money wise
That must be a long time ago, so someone wasn't 100% sure what was going on.
NHS salary sacrifice as done as lease contracts via third party, there are all kinds of tax/pensions stuff going on. I've not heard of anyone been able to 'buy out' a NHS salary sacrifice car. I'm pretty sure you need to pay some kind of BIK or resale tax even if the company let you buy out the car.