"While I was away I got a call from Mark Mapletoft [England A head coach] talking about how well Bats had gone there but he's not going to be able to make it.
"He had a scan and he's got a slight fracture in his leg, so at this stage Bats will be unavailable.
"We're hoping it's not too bad and he should be back maybe [for] the Leicester game."
Bristol play Amptill in their final Premiership Rugby Cup pool game at this stage of the competition on Sunday, before a five-day turnaround to the return of the league with a game at Harlequins on Friday, 29 November.
They then start their Champions Cup campaign with two group games at home to Leinster and away to La Rochelle before the Premiership trip to Leicester on 21 December.