I used to cycle to the Humber Bridge Country Park, to avoid roads.
There are also nice routes near Costello Athletics track, as many of the paths have grass alongside them.
For a more challenging workout, it's great to cycle to Beverly and run around the Westwood.
Cycle routes are always good running routes, as they tend to be along old train lines, such as the one starting in East Hull, which goes to Withernsea. however, they are usually hard surfaces, so best avoided.
If you want hills nearby, go to Hessle, where all the 'posh' houses are; the hills are never very big, but there are usually 2 or more close together to create effective training.