Legislation to outlaw squatting in England and Wales becomes active at midnight on 1 September.Part of the Legal Aid, Sentencing and Punishment of Offenders Act 2012, the law is intended to make the police act in all cases where trespassers occupy residential property.
The law covers all structures built or adapted for residential use (possibly even caravans), but not land next to buildings (eg gardens). Current tenants and tenants  at the end of their agreement are also exempt.
Ministry of Justice circular say the law will  landlords, homeowners and local authorities.