These are open road events, and the course - which follows the main A590 road from Levens to the Meathop roundabout and back - carries quite a lot of traffic. For full details, see the course description here. The minimum age to ride is 12 and all under 18s must have parental permission on the CTT Parental Consent form (which can be found here).
Of course it depends on conditions on the day, but if it's not too blustery the L1015 can be a fast course. Back in 2006 Bradley Wiggins set what was then a new competition record, averaging 33.4 miles per hour to finish in 17 minutes & 58 seconds (the Men's National 10 Mile Time Trial record is now held by Alex Dowsett, with 17:20).