Was a bit apprehensive but determined to give it a go. I knew I'd be last and made them aware before we started that I'd be slow but they said it wasn't a problem, someone would run at the back with me. They were very welcoming and I had a really nice girl running and chatting with me all the way round. The route was a bit longer then their normal one, almost 6k, and there was a few stops waiting for lights to change, dodging tourists etc. (the run was in London, over Tower Bridge and round the City).
Will definitely go again and hopefully improve.