Schools can choose to ban or limit the use of smart phone or tablets on school premises during the school day. Schools should make any policies on smart phones or tablets known to all staff, pupils and parents. These policies should outline any sanctions that will be imposed if pupils break these rules.
The Bennett Review of behaviour in schools includes a chapter about the use of technology in schools and case studies of policies in place. The report, which was published last year, can be viewed here: https://www.gov.uk/government/publications/behaviour-in-schools.