The Teynham 10 is a walk of 5 miles and should take around 2-3 hours depending on find speed. Number 13 should be given the maximum level of stealth and is the meanest seeing as it's no 13!
Puzzle #1 was a wordsearch, which can be found here...
Puzzle #2 was a number pyramid, which can be found here...
You will need to solve and visit those caches to collect the North and East coords for this physical cache.
Please note this one in the summer is harder to get, and gloves may come in useful.
The cache can be found at...
N 51 (puzzle #1 cache bonus)
E 000 (puzzle #2 cache bonus)
If you want to double check the answer...

Congrats to SAS&A1 on the FTF of the entire series, and special thanks to them also for all their help in the snagging of these puzzles.