The drug needs to have a proven benefit, which usually comes down to how much longer does it give you, if it's only marginally better than the existing treatment, but orders of magnitude more expensive they work with the manufacturer to bring the cost down to where it can be approved.
A lot of what was written about the UK system during the ACA debate was outright falshoods or misrepresentations (e.g. the infamous "death panels", whilst ignoring the Kafkaesque nightmare that can be the US system).
Tell you what, I'd take the NHS over what you've got any day of the week, as would the vast majority of people in the UK.
There isn't a "british" system because health is devolved. There are four separate systems, one each for Scotland, Northern Ireland, Wales, and England.
> requires a stringent cost-benefit-calculation
There are lots of problems with the English NHS, but this is almost never one of them. Unless you have particular examples?