I have an old canondale tourer which I am using as a cyclocross frame.

I want to swap the heavy steel fork for a carbon fork with disc tabs.

The frame has a 1 inch steerer.

I was looking at options and Nashbar do one but do not ship outside the states.
Any other suggestions

Exotic do some 1 inch steerer MTB forks

Depends on how you feel about aesthetics I suppose

http://www.carboncycles.cc/?s=0&t=0&rb=14&#MTB_Carbon_3K_with_1.1/8_inch_Steerer

Looking for 700c forks.

Did the 3 peaks cyclocross this yearand they stipulate that you need 700c wheels.

Croix de Fer owners (including myself) have the same problem.
straight 1 1/8″ steer, disc tabs (post/IS don’t care), room for 35-40c, qr/15mm axle.

Right now the only option that suits the purpose is the pricey Ritchey
http://ritcheylogic.com/wcs-carbon-disc-cross-bike-fork

You can get those Exotic forks linked above in 1 inch steerer, 46.5cm length (i.e 700c).
http://www.carboncycles.cc/?s=0&c=82&p=966&tb=001

Road / CX forks generally 400-420mm a/c dimension – a 460mm fork will result in a 2-3 degree ‘slackening’ of HTA which will change handling. Think there’s a shorter version.

Goes fat bird cycles had a 11\8 straight fork van Nicholas which might be of use

OP I assume you need canti bosses?

Otherwise those Exotic forks come in a good range of lengths

Not if there’s a 1″ steerer tube

eXotics on eBay come in 39, 42.5, 44.5 and a 29er length Axle to crown.
The best product I’ve found is £136 carbon bladed number on bikediscount.de, 40cm. These are all to fit my 1&1/8th not 1″ sorry.

Exotic do a 1″ carbon fork 39cm axle to crown with disc mounts

http://www.carboncycles.cc/?s=0&c=82&p=966

The also do it 42.5 cm