I can't see why Rob wouldn't be allowed to visit Jack in HMP wherever. Ursula is probably right about problems with a long journey (for Rob,given his health) but as he and Helen are married, Rob has PR and also as we all know, care of Henry so I can't see any reason a request to have regular contact would be refused.
Even if Helen finally begins to talk about his abuse of her and Henry he'd still be given contact. So here we go, how is this going to be dealt with. I can't imagine the prison is in a position to supervise contact in this kind of situation.