Ooops, didn't see the bit about *how* to pay, heh
Yer, there's attended lanes where you will get change, or automated jobs, where the exact change in coins is needed, or a debit / cred it card.
On the subject of whether to or not, I'm inclined to take Drifty's view - use the toll, cos it's quite easy for the journey from the M54 down to Spaghetti to take over an hour more than what it should, due to traffic, especially on Bank Holiday's.