How is it that coaches are allowed to be 15m long nowadays whereas a lorry / truck / wagon can only be 12m (or has that changed too) Can these longer coaches only be used on certain routes?
Think you will find that artics are longer than 15mtrs…I hope 
Is there a max length for an 8 legger?
Err, I meant rigids.
There’s deffo summat in C&U about it and the effect on the turning radius, but surely if a coach can comply… I’ve never seen a rigid 12m+ other than a concrete pump or mobile crane.
Not sure were you got the 12m from, As I think the max length for an artic is 16.5m and the trailer is allowed to be 12m from pin to the back and 2m in an arc from pin to the front, so you get a 13.6m trailer.
And I thnk Wagon and Drags can be slightly longer.
Concrete pumps I believe dont come under usual rules and regs, as they run on red diesel and up to now can be driven on a car license, there were plans afoot to change that, so dont know if its changed yet, believe cranes could be the same??
The mobile plant exemption from driving licences has disappeared although I think they still run on red and could well be exempt from tacho hours.
If you Google “max length vehicle” there are numerous links to DFT and VOSA pages that state 12m for a single vehicle, how up to date I dunno.
[Urban Myth Alert] My coach driver friend told me if they have a steering axle on the back they can be 15m[/Urban Myth Alert]
I have no idea if it is true, although I’m doubtful but I thought I’d post it up and let DI Rog have a crack at investigating it before someone who knows what’s what comes along and gives an authoritive answer.
On buses, does a bendy bus driver need a D + E licence and also are they restricted to max and axle weight limits?
Yes, they do need D+E, because it’s bendy, and busses are also subject to the same axle weight limits as we are, they’re just designed not to be able to pack in enough people to go over them.
Bendybuses only need Cat D, Not D+E as its considered that because of the trailer section cant be detached that it would be CAT D
muckles:
Not sure were you got the 12m from
It’s correct, 12m is the max. length of a rigid goods vehicle. As for buses, it’s 13.5m for a 2 axle and 15m for over 2 axles and you don’t need a DE for a “bendy” bus 
Now we’ve mentioned them on here I saw loads of 15m coaches yesterday.