Many thanks for the various useful comments & suggestions.
Old Barry - yes indeed!. I was trying not to mention the current hospital as I'm still hoping they might get past the obstacle to anaesthesia. It has necessitated referral to another department, and various tests have been done quickly, but as the non-prostate medical issue gives no symptoms except under anaesthesia, and might not in itself need any treatment, it isn't seen as urgent for followup. The result is more months of uncertainty and delay while urology await the outcome of referral to the other department.
Microcolei - I'm comforted by your experience of EBRT with Linac machine but I would still be happier with brachytherapy inside my actual prostate, preferably in the one lobe, since unlike you I'm not thought to have cancer anywhere else, not even locally. Well not yet anyway but the longer it's left untreated........
Andy62 & others: how long a wait can I expect, if I ask to be referred on for brachytherapy at Mount Vernon? (under NHS). If it's really long, how expensive would private be for brachy? At Mount Vernon, Birmingham or elsewhere. Private hospitals seem reluctant to reveal self-pay charges but I've heard that any form of radiotherapy might be £40k+ !