Hi, Like you I had surgery on skin cancer, though non-melanoma, and was advised it was the gold standard. Although they say outcomes are very similar with Prostate Cancer for surgery and radiotherapy.
Also it would be unusual for a case not to be reviewed by an MDT and it appears they've said you will have both surgery and radiotherapy. It's unlikely you'll have surgery after radiotherapy and unlikely you'll have it when you're over 75 unless you're exceptionally fit.
There are papers that say getting rid of the main tumour, i.e. cutting it out, is beneficial in the longer term.
It's often said Prostate Cancer is slow growing but with a 4+3 it might not be the case and actually having surgery will let you know if 4+3 is genuine as mine was upgraded to 4+4 with a proper pathology test, or maybe a later time. Upgrading isn't unusual.
Having second thoughts isn't unusual either as I kept thinking it but if it complicates matters and raises suspicions about your doctors and them about you it might not be for the best.
So assuming you've been through a standard procedure and will have surgery followed by radiotherapy going with the flow could very well be the safest route.
Also having radiotherapy quickly after surgery is called adjuvant radiotherapy and for most cases has superior outcomes to having just the one treatment although it's usually only given to cases with the potential of recurrence. Having radiotherapy after it's recurred is called salvage radiotherapy and the outcomes aren't as good. So your case looks like good treatment.