Google UK is now allowing advertising in their AdWords for gambling associated ads by online gambling companies to target Great Britain (England, Scotland, or Wales) as long as the advertiser is registered with the Gambling Commission and provides a valid operating license number. Advertisers based outside the UK and within the European Economic Area who wish to target online gambling ads to England, Scotland, or Wales must be licensed to advertise online gambling in their respective country.

More info: Google UK Rules and Application Process