That's what the RAT is for. It gives 2500psi to the blue system, which leaves you with all control surfaces operative down to 125 knots.
Near enough what I was going to say, as I couldn't believe anyone would consider the N1's 'windmilling action' as a reliable form of emergency power. That's what the RAT and APU are for, and as correctly stated (I didn't know the numbers) the RAT will provide you with full hydraulics to the essential control surfaces right down to the numbers.
That's good enough for me
