Yes, £2 to park, trails start a short way from the carpark, and are not through the gate by the Go-ape itself, go out of the car parking area past the look out centre with the centre on your left and the road on your right and they're 100m up there.
There are 3 loops, a short green, really for kids and total beginners, and then a blue loop from the start and a red loop that branches off part way round the blue. So most people set off on the blue, do the red, and then the second half of the blue.
Total is about 14 miles actually, and in dry conditions, balls out I can just about do it in 80 mins. But with this weather while it will all be rideable still, it can get a bit heavy in places, so I'd allow easily 90-120 mins for both. Way marking is pretty good, at the end of a section, there will be a direction arrow on the post, or follow obvious tracks. And do go cautious on a first lap, while there arent any major obstacles there are a few sections that have rollers that can get a bit large if you're out of control; the air ambulance has been known to visit in places.
Lastly, in the weather we've been having, bring spare brake pads, swinley paste can eat sets very quickly.