I've treated my road bike to some 'new' forks (old style – still 1" threaded steerer jobs) and where the carbon fork's crown is wider than the old forks, the fixing bolt on my brake calliper isn't long enough to reach the nut. Can I get a longer nut to reach the bolt? or will my bargain forks turn out more expensive than I thought cos I'm now going to have to buy a new brake?

Yes you can get a longer nut. From CRC, i bought one last week when i put carbon forks on my winter bike.

Search "for sunken nut".

Yes you can get a longer nut, there are 3 to 4? diff lengths nuts you can get. a good bike shop should have some spare ones tucked away somewhere.

CRC
SJS cycles

Ah, excellent. I love you guys.

Been in Haants, are you going to the southern champs this wkend?
If so might be able to help you out!

Nice offer, thanks. But no, my son's birthday so gotta take him and his 2 mates out. 8 year olds. Help!
I need a 30mm, CRC only have 12.5 or something so have ordered from ebay.
Will pop into Hargroves tomorrow as the Ebay seller is in the far east.
SJS Cycles wanted £10! £6.99 +postage! Flip.

my son's birthday so gotta take him and his 2 mates out. 8 year olds. Help!
Take them biking!
Ok shame you not racing, not sure if I got a 30mm but I have a look in the next day or so.

Thanks mate. I'm retired from racing 🙂

Happy lunchtime! Rode down to Hargroves, "Yes, sure" says chap behind counter. Produces the perfect size nut from the workshop and charges me the change in my wallet (ie. not much).
Brill. 🙂