The fly-half has been sidelined with a chest injury and there had initially been fears over his early involvement in the Championship.
But he was selected as one of two fly-halves in Rob Howley’s 35-man squad and has now returned to the pitch.
Hook came on as a replacement in Perpignan’s 40-22 Amlin Challenge Cup triumph over Rovigo last night.
With Rhys Priestland ruled out of the tournament following Achilles surgery, Hook and Dan Biggar will battle for the number 10 jersey.
