Even if the OP had didn't have enough cash on him to pay the £1 toll, I'd
hope he would have had a credit or debit card. Not really advisable to
drive around without any method of paying for things!

Is there a staffed desk? Maybe there is a system for taking down number
plates and billing you later. Through the hastle of checking the
numberplates (with the DVLA?) and sending out a £1 toll would probably be
not worth it, so they may let you off. There could be a £10 penalty fare.
Who knows?
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