BC printed voucher no longer needed. I have found that the deal you get can depend on the staff member. Bought some tyres for click & collect at store near work with web discount and the manager wouldn't let me have the BC discount as well, saying it was only available when paying full store price.
Bought some rollers last year. Ordered vouchers through my work benefits scheme, (pay 90p in the £1 for them), ordered rollers online with the (then) web offer and when I went into collect them, asked the young lad on the counter if I could use BC discount. No problem

. Guessing they didn't do too well out of that deal.
I've also done a web price match in store for a bag and used BC. Have to say that the guys in the cycle section of my local store seem pretty switched on and one in particular is very helpful.