I think you only get a discount on transactions paid for through the till in store so it's extremely unlikely. Might be worth doing sums on buying on a 0% cc with bc discount. If a halfords bike in the oneJust managed to find their number, unfortunately "No" is the answer. Will pop into local branch and see if anything changes there.
You do know that you can use the Halfords scheme in other local stores, get in touch with Halfords customer services ( I used facebook to message them) and ask them what other stores in your area accept the scheme I've got a Giant TCR awaiting collection once I've got my letter.