For those wondering how riders learn the TT...it goes something like this. Could've typed it up myself but this is lifted from an online forum to save a bit of time:
The IOM TT course is the ultimate road racing course you build up experience elsewhere before you attempt it.
IOM TT newcomers are not newcomers to road racing, they will have competed at the smaller events in Ireland and N.Ireland and the mainland, so they are not wet behind the ears road racing virgins. Guy Martin moved to Ireland for a few years, entering the road racing championships, (and winning them), before he attempted the TT course.
They have been talking about this subject, on the radio.
The newcomers are coached by a few people, ex riders, they're taken around in cars and told where they should be on the road, they drive or ride the course as many times as they can. In any spare time they have they watch on board laps over and over again.
To race at the TT, first you must race in the Manx GP, on the TT course. The newcomers to the Manx GP do their first couple of practice laps under controlled conditions, they are lead around at a slower pace, by either a travelling marshal or a more experienced rider.
They are then let loose on the course, however they are told to keep a steady pace and not to expect to get any faster until they've completed fifty odd laps, this could take a few years!