Lyn,
I don't think my hospital prescribes tamoxifen, or daily low dose tadalafil, or metformin to prostate cancer patients, and doesn't offer the breast bud RT blast.
It's a matter of arming yourself with the information (and this forum is a fantastic place place do do that), and then if necessary going in search of research to backup your request, and putting that to your healthcare professionals. I won't pretend it will always work, but that's mostly worked for me. In the case of tamoxifen, I had to ask different people about 3 times, before the request went to an oncologist (who I never met) who prescribed it. The first 2 tries were met with a refusal ("we don't do that"). The request for breast bud RT blast was always a refusal, but in retrospect I prefer that I went the tamoxifen route, after having read comparisons of the two methods.
It does help that I have an excellent GP, but that's because I tried various of the GP's in the practice, and stuck with one I thought was particularly good. If you don't have a supportive GP, then it's probably worth looking for another one.
Also, make life easy for your healthcare professionals. I turn up to appointments with things like a spreadsheet of all my blood test results, which is much easier to access and read than anything they can get from their computer, and another spreadsheet which is a diary of all significant tests, treatments, etc, so I can easily say "I've been on Zoladex for 8 weeks" or whatever the query happens to be. I also keep a list of all my medications with doses, why they're taken, since when, etc. and I must have given out around 6 copies of that over the last 3 months treatments. The response is always the same - "Wow, I wish everyone did this". So do it. It's all on the NHS computer and hence unnecessary in theory, but clearly it's a massive help to them. When they see that you understand your disease and treatment, they are much more likely to listen to your requests for specific medications, because you probably understand why you want them too. If there are things people don't understand about their disease or treatments, then ask here.
Not everyone wants to know about the disease. I had my brachytherapy with 2 others who wanted to know nothing about it, didn't even want to look at their catheters. That's a coping strategy which probably worked for them, but wouldn't work for me. The knowledge I've picked up along the way has modified my treatment path, something I would have missed out on without it.