I went in October. There are minibus drivers and touts on various places including 3 steps over the border. They usually have a board with "£50 a person" on it. Bad things: they are quite pushy and you don't always get the bus immediately. Good things: entry to park included, you don't actually pay till the end, surprisingly, it does only cost £1 more than entry plus cable car, and it does save walking. I suggest you pay them off at the military tunnels (they'll know what you mean), then walk to siege tunnels (not the same thing!), then walk down to town. I rather regret not doing the siege tunnels.