Go to a solicitor and in addition to the police report/crime see if you can pursue a civil case against both the woman and the brewery/pub - worth going after both in case she's on a low income and comes up with some BS about how she can only afford £1 a week. -
Edit - if it's a registered XL Bully (might well be given the muzzle) then she's required to have third-party liability insurance ergo definitely sue her - you're potentially owed a few grand:
Tried a quick google:
If the police are otherwise being lazy then at least there could still be some consequences for her but really they need to both confiscate that dog/put it down and ban her from owning a dangerous breed + criminal punishment and a payout in civil court too - ditto to the pub, staff were negligent and helped cause that after being told about the danger - pub (hopefully brewery chain as a whole) might be prompted to update their guidelines/staff training.