Wild Farm in Radlett. Owner is a Grand Prix rider. Lovely listed courtyard, long arena, post and rail individual turnout and off road hacking. 07590 058954
I will follow your post with interest. The major competition centre that shut was reputed to be changing hands for many millions of pounds. I don't know how we can raise enough funding to save it. The first planning application for housing was withdrawn but I don't think it will be long until a...
There are some yards in Harefield, Northwood and Hayes. Morden is not an option as way across the other side of London. Perhaps people who have contact numbers could post. Otherwise it is worth looking on the notice boards of tack shops including Old Horse House, Ducks hill, North wood.
Try Abbeyfields in Hayes and Littlebourne in Harefield. Both have websites. It's also worth contacting Gould's Green. It is a riding school but may be able to suggest places in the area. There are several in Harefield.