Andrea,
Sorry I can't help regards recommending someone who could further your interest in speed walking. But don't dispair- seek and you will find. I've always had an interest in walking quickly. I've found it's less harmful on the joints than running. Years ago I used to walk the Pennine Way, I liked it so much I did it several times, then even went down into Surrey, over a decade to compete in a 100k walk they put on each year, round April time. It was fast and furious and mostly off road but I loved it, mainly because It didn't hurt that much so I was always willing to push-on. These days, after many years of just running I'm enjoying quick walking again, using half my running time and it's suiting my life style. On certain days through the week I leave the front gate with a spring in my step, off up the road. My neighbours must think I've a screw loose on seeing this old man with arms swinging, passing their front windows. In past times I'd have flashed two fingers there but these days, I suppose, one would be sufficient. A thing I have learned about fast walking is , one must always focus otherwise the pace will drop. If the mind wonders onto trivia you may as well give up - which wouldn't do. So go for it, Andrea. You've nothing to lose and possibly much to gain.