For Focal therapy, of which there are several kinds, HT is not offered as part of it to the best of my understanding. However, after it was evident that my first HIFU treatment had failed , I was prescribed Zoladex but with some encouragement from the Royal Marsden I held back on HT as I knew from early experience of it prior to initial RT, that it caused side effects I did not wish to have again. Eventually, as my recurrence seemed confined to my Prostate, UCLH agreed to a repeat HIFU which a couple of years on is still giving a satisfactory result. I understand that should a new tumour grow in my Prostate a further HIFU or other form of Focal Treatment will not be given, so I would then be offered HT again. (I am 87 now and in the event of this happening, I would be more disinclined to start HT with each passing year. A younger man in a similar position might be more willing to have HT).
Whilst you can't look very far ahead, I think it is prudent to consider the implications of a failed form of treatment and options that would be open to you at that point.