Well, I returned tired, but happy.
Many thanks go to Martin from SWCC for offering to take me down Ogof Ffynnon Ddu at such short notice, and for supplying me with the equipment to do it. Here follows a short run down of my day...
5am came bright and early, which was 2 hours earlier than I needed to get up. No way could I get back to sleep though, so I stumbled out of bed to await my departure time. It took about 3 hours to get to Penwyllt, including a petrol stop, which was about the length of time I was expecting.
After ten minutes wandering around the SWCC cottage, feeling a bit like a spare tool, I bumped into Martin who gave me a quick run down of the place, followed by an introduction to the equipment: oversuit (with worn away bum area), belt, helmet with lamp, and a pair of very useful rubber gloves (hands didn't feel cold once!).
And off we set, with Martin explaining about the area, the cave system, and other stuff, as we walked up the hill to the cave entrance.
I say "hill", but really I mean "North Face of the f***ing Eiger".

Martin's patience must have been well and truly tested, although he didn't show it, as I had to stop 5 times on the way up! My lower back muscles were aching like hell, and cramping up, and I was more than a little concerned that the caving trip wouldn't be able to last more than 20 minutes at most. However, when I was actually in the cave there were no problems.
After a brief stop outside of the entrance, which I think was more for me to get my breath, we ventured inside. Which is where I had my first surprise: it's very rocky in there :

. With Martin traversing the ground like a gazelle, and me following behind like an oaf with two left feet, we went a short distance before stopping again to let our eyes get adjusted to the level of light.
Cutting a long story short, we covered a few different types of ground, with Martin explaining as we went along: cave ecology, what the tape on the ground means, general safety, etc. The most important lesson for me was when we came to a chimney that dropped down to another level. I had no problem (psychologically or physically) gettting down the thing, but before I could do so Martin stopped me and asked...."How will you get back up?"
Hmm, important lesson learned: don't go down anything, unless you're sure you can get back up. :-[
Martin then showed me how to get back up, and I had to admit that I didn't have the confidence to do it (shorter legs, and unsure of my footing this early in). So we reversed slightly, and followed another route down.
Up until this point, the passages had been (to my surprise) very large. So large in fact, that I didn't really feel that I could get a proper scale with only my headlamp. This changed a little when we came to the 'corkscrew', which was a simple drop and twist next to a fecking large hole.
Hole avoided, we passed on down and came to a two way stream bed. Given the option of following one of the branches, I decided to go for it - the narrow, twisty branches..... which I enjoyed immensely! I did, however, find that this was the place which showed that my lovingly developed beer belly was not an asset. This was the first area that really tested my (lack of) stamina, with the twisting and turning, and the exertion of it had me feeling physically sick at one point. At the end of the stream, I was rewarded by the view over a large drop into darkness (and another lesson learned: large holes might appear out of nowhere :blink

. Back to the junction, and Martin offered to show me the other branch: equally twisty, but with some wonderful white icing-like formations 'dripping' from the roof.
We'd been underground for a couple of hours by that point, so it was decided that it was a good time to head back to the surface. Lesson number 3: going down is faaaaar easier than going up. I was kind of hoping we'd go
down a bit further, and then step out of a hole back into the cottage changing room. You know, like in Mr Ben. 'twas not to be though.
We ascended to the top of the corkscrew, and then headed off to a rather large cavern called The Big Chamber Near The Entrance. It was admittedly a chamber, and rather big. I shortly found out that it was near the entrance too. The early pioneers certainly didn't mince their words.
And here, in TBCNTE, I discovered my forte: modelling. Martin had brought photography equipment along, and I proceeded to strike various heroic poses while the tiny magical box recorded the moments for posterity.
A short trip along a (fairly) smooth passage later, and we were back at the entrance.
It was very strange, climbing back out to ground level. The outside scenery seemed oddly different to when I had entered the cave. No matter, we headed back to the cottage, and I availed myself of the lovely warm showers there.
It was a wonderful trip, which I can't thank Martin enough for. The advice and commentary about the cave ecology was both invaluable and interesting, and at no point did I feel pressured to do anything that I didn't feel comfortable doing. I felt challenged, mentally and physically, but I always felt safe (well, as safe as you can be when you're challenging yourself in a cave). My only real concern was afterwards, when I noticed a long brown stain on the back of my jogging bottoms. I felt sure that I hadn't been that nervous in the cave! And then I remembered that the oversuit was worn away in that area, and open to the elements. Phew!
So, a great trip. Were there any disappointments? Yes, one, but one that didn't occur to me until afterwards. I didn't get to see much of what was around me while travelling over the rough ground, due to my having to pay attention to when I was stepping, and the lamps don't illuminate a lot. My footing will (hopefully) improve with practice, but the illumination cast by the lamps isn't going to improve all that much. Therein lies my disappointment: I will never be able to see the true splendour of the caves and passages, except through photography afterwards, which is a little sad. The various photo's I've seen (Martin's, the ones on the SWCC website, etc) show an amazing world that people would pay good money to see. The reality is that the only way to see it 'live' is to take a lighting crew everywhere you cave, which isn't going to happen. The disappointment doesn't detract from the caving trip itself, but it definitely set up a yearning to see the wonderful places as I travel through them.
And best of all? Very few aches the next day, and no pains at all.