I thought I'd follow up after the event, which was yesterday.
It was a really great event, and I'm very pleased I went (it involved cancelling something else for me, but was well worth it). I'm guessing there were about 50 people there, but could have been more as not everyone was in the Musette Cafe (base camp) at the same time. These were mainly PCa patients, but also several PCa consultants, some family including children, and an exercise trainer. I got to meet a couple of the other consultants in the team who I might see during my treatment (and his family in one case), in addition to my current consultant.
The format was to all meet in the Cafe at the start. Apparently, there's sometimes a talk at that point by one of the medical staff, but with this being an open day and lots of new people, the talk was by Charles the main organiser, explaining what Prostate Peddlers do.
After that, we split into different ability groups. There were two groups for existing cyclists, a mountain bike group, and a road cycling group. There were also two groups for new cyclists, and some people stayed in the Cafe and didn't cycle. I'm normally a road cyclist, but as I'd brought my mountain bike along, I joined that group. I was wearing my tracking device, and checking that now, we did a 10.7 mile trek through the woods. It wasn't at all hard going - not everyone had mountain bikes, and there was even an electric bike on loan which a few people tried out during the trek. I consumed 750 kCals over the 2 hours, but there was nothing strenuous. There were a couple of stop offs, and we were going slowly enough to be talking with each other all the time - much of which was about PCa, but plenty of other conversations too, certainly about cycling and other exercise (we had a trainer in our group too). I believe the groups for new cyclists drove them up to the top of a nearby hill, and they cycled back down the country lanes to the Musette Cafe. These two trips were at different times, and some people might have done both of them.
As we arrived back at the Cafe, hamburgers were being cooked, which was very welcome.
Also, there was a 1km race on a timed exercise bike. When I had my turn, one of the consultants was in the lead at 1:34 for the 1km. I came in at 1:33, and no one else beat that, so somewhat to my surprise, I was the winner of a bottle of champange. (The consultant should get one too, as there was one for the best medic, and one for the best PCa patient, so he shouldn't be too annoyed if I see him at my next consultation;-)
The weather held out - just. It was a bit cold - I had to scrape the ice of my windscreen when setting out in the morning, and it was hovering around 6C most of the day, but there were some sudden dips in temperature. After the event finished and we were clearing away, we got a few mins of sleet/snow, but fortunately not during the cycling.
They plan to repeat this open day in the autumn, and then probably continue each spring and autumn. The Prostate Peddlers themselves meet up much more often than that, and I guess we'll be getting details as they hope many of us who came along for the open day will join. My consultant is also one of their key supporters, believing strongly that exercise is a very important part of the treatment for PCa, and it was he who originally made me aware of it, when I turned up to a consultation in my cycling gear.