hi
You should be getting into your marathon training by now, so that does included hill repeats , that is what you need to be doing plus training on a hilly route or entering 10k or longer races known as hilly to get you happy with hill's, this will increase your confidence to tackle hill's and make you stronger for the marathon.
There is ample parking in side streets and car parks but I don't know if they charge on Sunday, the race starts just of the town centre
my advice is to take easy on the first section as this where the hill's are (there are a couple of pubs on the route if you feel like stopping, though not a good idea.) but there drink stations where you need them.