I did this as a single lap route starting at Warwick University.
To start head up Gibbet Hill Road and at the crossroads with the Kenilworth Road go right and head towards Kenilworth. The Kenilworth road becomes the Coventry Road and you're on this from the traffic lights for about a mile.
Just over a mile down from the traffic lights you'll find a sign post for a Public Footpath - this is part of A Coventry Way.
Your run this path right to the end up until Berkswell. There are lots of turn offs if you fancy a detour but I just ran straight through first time around. There aren't too many hills but there are a few muddy patches on the route. Towards Berkswell you'll come to a t-junction where the path appears to end. Bear left down the path then right accross the field and you can head towards Berkswell train station.
This takes you onto a road/footpath section of the run starting on Truggist Lane. Follow this until you see a right turn onto Hodgett's Lane. Take the left onto Cromwell Lane. Turn right onto Westwood Heath Road and you're back down to Gibet Hill Road.
A great run - lots to see on the way round, more bridges than i've ever seen!
You can find more details at A Coventry Way.
View Running route - single lap taking in part of Coventry Way in a larger map