From what you say it does look like his PCa is advanced, and very possibly beyond the point where surgery was considered an option. The hospital to their credit did start him on HT immediately, which should help restrain his cancer at least for a time but very poor that his situation was not explained to him. Only after the bone scan has been considered will the diagnosis be complete and communicated to his GP and to him. He can ask to be copied into all correspondence about him.
The nurses on this charity are said to be very helpful and if it has not yet been obtained, a copy of the 'Tool kit' which explains much about PCa and is available from the publications section of this charity in the main part, could prove helpful.
It might be worth contacting the 'PALS' people at Whipps X to express dissatisfaction about inadequate communication and explanation so far.
As regards moving to another hospital, I think a referral will need to be made by your partner's GP or from Whipps X hospital if the latter is prepared to make one.