Sorry to hear this and is a horrible position to be in.
But what has this got to do with budget? It's a trial, assume it's got a license as you can buy it. So it must be how effective it is. Not much point giving it to everyone without knowing effectiveness. Trials full and when NHS gets results they'll decide if it's worth it.
This is it basically, what do people want the NHS to do, spending 50million on adding more people to the treatment, thats in trial, and find out in 3 years that the treatment works temporarily but caused every last patient to die of liver failure?
In which case you'd be happy your dad couldn't afford it, or very angry the NHS wasted so many millions on a drug that killed patients without a proper trial.
Medicine is trial and error, many millions of people die worldwide waiting on new drugs to be proven to work or not work, unfortunately thats life.
I'm not having a go at the OP, its a horrible situation, but that 37k the NHS could fork out might be for a drug that doesn't work, and that could be 37k they take away from treating someone that would have cured someone.
In terms of no budget on healthcare, thats mental, unlimited funds spent curing a 95year old person of cancer, to have him die of old age 3 weeks after its cured, etc, etc.
The NHS does have FAR too much waste and could spend a lot more on actual healthcare, thank Labour for that, so many people and paper pushers who do nothing remotely worthwhile. However a "real" government would both not have hired so many useless people AND wouldn't have spent us into such massive debt so there wouldn't actually be a lot more money spent on health care, just a lot less money spent full stop.
This is really why the "star trek" society, where there isn't money, and people aren't greedy, and we just do what needs to be done would be very very useful.
But even then, while they'd maybe give you the option to be part of this trial without any cost, it still might not work or could be wrong for you, though personal choice is pretty important, feeling like you're dying because you're being denied treatment, than trying it and finding out it doesn't work would be a horrible experience.
TO the OP, hope your dad finds a treatment that works for him.