J1M has it spot on. DO NOT try to do too much now. A final long run of around 9-10 miles, two weeks before race day, with another of similar, maybe slightly shorter distance before that (either this Sunday or next) with some shorter slightly quicker stuff thrown in during the week should be fine.
I've done three half marathons (all Bristol actually) and have never gone more than ten miles in training for any of them, because each one was after a break from running, so effectively I was starting again. My next one will be slightly different in that I have been training and getting a good base for much longer, so I should be able to get some higher mileage runs in before the race. I know I can do this because I'm three months out and have already done some long runs of similar distance to the longest runs I did for the last three.
Good luck and enjoy it. You get good support at the Bristol Half. I'll definitely be back there at some point in the future to try and smash my (slow) PB.