12mph seems very slow, but I suppose you can still cycle in the carriageway if you're a decent cyclist?
Really we need to ban motorised vehicles that go above 12mph. They are not bicycles and should not be in cycleways. I feel there is a big difference between someone who is able to pedal at higher speeds and someone who is just using a motor vehicle.
Cycling on the road is only allowed where there are no bike lanes, which is very rare.