I've been trying to use one of the three planning-portal approved map providers on-line tools to generate the location and site plans I need for my planning application (large summer house in my garden). I'm finding it very difficult to add detail such as the proposed new development (summer house) outline into the site plan using any of the tools that are suggested. I was wondering if there is a better way? I was thinking that perhaps I can simply download the basic map and then edit it using some other more user friendly tool. Suggestions?