Hi Natalie,
Yes, there is a section 18 (well, two actually).
I'm afraid I'm the guilty party here and I must apologise for putting the WRONG numbers on 18.
Section 18 is split into 2 parts and sits between the two 13's and the two 20's.
If you click on the map on the first page of this thread and save it to your computer, you should be able to print it out. If however, you intend to visit St. K's, I believe a section map has been erected at the entrance.
Anne