You definitely don't need a 4wd to get to the glow worm tunnel car park. It is a perfectly good all weather road. So long as you don't drive a semi trailer or have a tall load, because you drive through another tunnel on the way to the glow worm tunnel

The only problem would be at popular visiting times, the car park is quite small and can run out of room. The walk from the car park to the tunnel is not difficult. Can't have been if I made it there and back Very pretty.

Remember, glow worms can be sensitive to noise, and turn out their lights. Move quietly and go into the tunnel until it is very dark. Turn off your torches and stand quietly for a little while, and hopefully you'll see all the little stars of light. It can be difficult if lots and lots of other people are going through at the same time.