If you go to a police station then they may be able to help you, depending on whether they offer this service. If they do, a friend or family member must deposit some money at their nearest police station. When this has been done, that police station will contact the police station you are at and they will release the same amount of money to you.
An alternative solution would be to use a public phone to make a reverse charge call to friends or family who can help you get home. For example, they could get a taxi to come and collect you and pay for it when you arrive, or they could find a taxi/hotel company that will accept card payment over the phone. Alternatively, there are a number of money transfer services available throughout the UK.