http://www.homeoffice.gov.uk/crime-victims/reducing-crime/prostitution/

In April it will become an offence to pay for sex with someone who has been forced, threatened, exploited or otherwise coerced or deceived into providing the sexual services by someone else who has engaged in such conduct for gain. If convicted of the offence you could face a fine of up to £1,000, a court summons and a criminal record and risk having your name mentioned in newspapers. It will be no defence for a person to say that they did not know the prostitute was being forced or threatened.

The laws on kerb-crawling are also changing If convicted of kerb crawling you could face:

a £1000 fine
losing your driving licence
exposure of your habits to family, friends and work colleagues

If convicted of paying for sex with someone who is under 18, you could be sentenced to a lengthly prison term. The maximum sentence for the offence varies according to the age of the victim and the sexual acts invovled.