I ran the half in 2012 and would agree with Lilytoo that there are some longer sections of "urban grit" through business parks / industrial estates with little or no support. Good support in places though with DJs in camper vans playing music and live bands.
I've got several pairs of Slazenger shorts from Sports Direct which cost about £4 a pair (which I wear over lycra shorts). All of them have two zipped side pockets. I think they might be classed as swim shorts as they have a mesh lining but they are fine for running.
I just hate going into Sports Direct as it always feels like a jumble sale trying to find anything.