Those who know better than me might be able to source data that allows quick preparation of all the roads and buildings but without the fine detail that can only be derived by careful surveying.
This urban sample was prepared using the Greenspace data for Scotland supplemented by OS MasterMap data supplied a under licence agreement with local authority/sportsscotland. Never left my chair.
I do not have OCAD but used GIS to mimic styles as best I could.