I'm looking at buyin a bike from halfords in the next day or 2. I've decided on the one i want, while looking online i have seen a 10% off voucher.

Does anyone know if this can be used with a 1/3rd off discount on a bike?

At a guess i would say no. Usually t+c say 'not to be used in conjunction with...blah blah' worth an ask tho!

^ I agree, "Not to be used in conjunction with any other offer".

probably NO