As a relative local married into a family of blue noses, my advice would be no colours if your spending time around town pre/post match.
Their nobs are of the highest order, a few years back we got started on by a group of about 10 16-18 year olds, 2 blokes and 5 kids under 12 of which 4 of us were actually birmingham fans.
Pay the £5 and get a cab from town to the ground and your be fine, they really do have too many cowards at look for small groups with women, children to try it on with.
The ground itself is a shithole, but appartenly give her your credit card and the bullring is great, (The square peg isn't a bad place to wait for them to finish shopping, decent beer and cheaps as anything)