We'll have to wait and see what the sentencing is for Watkins, but how bad a time he has relatively will depend on what prison he ends up in.
Doubtless he will be classed as a VP, a vulnerable prisoner, that goes with the territory of what he's done. But this might mean a dedicated and separate prison somewhere calm where he can get some form of analysis or treatment so he begins to understand what he's done. If he does ever get to the point where he's lucid enough to genuinely understand what he's done, that should be 'punishment' enough.
On the other hand, if he's in some victorian pile where they have a VP wing and a regime that tries to keep VP's separate from other non-VP prisoners then I'd expect most hours of most days he will be locked away and when he isn't locked in his box he will need to be on his guard for all the local hero's looking for fame.
Either way, whilst the sentence may not fully match the crime, he won't be having the x-box holiday red top papers would have you believe in. That's not to say that for some, the homeless, ex servicemen with problems, those with mental conditions or those from gang run sink estates, they can find prison almost a haven and do well in prison. But for this guy with this crime, this will not be a good time.