The TNF isn’t that good, the first section is ok as climbs go, the descent from Moor Top to the cafe is ok. The bit in between is fire road rubbish. I’m not even sure it that good for beginners, you kick off with a long and (for newbies) stoney climb which requires some technique. I know a few who have been put off by it.
However, if you put some time in to work out where the good bits of natural stuff are you can use bits of the TNF to advantage on your own loops.
Not sure if this was mentioned on the other thread but it is quite useful for plotting routes round the forest:
http://www.ridethelakes.co.uk/phpbb3/viewtopic.php?f=14&t=704