PLANNING AND BUILDING REGULATIONS
http://www.planningportal.gov.uk
The Planning Portal is the UK Government's online planning and building regulations resource for England and Wales.
https://www.gov.uk/browse/housing/planning-permission
Another government's website with information about planning and building regulation rules in UK.
Check also your Local Authority website, and search for Planning. There will be plentiful of information about national and local planning requirements. Some council's websites offer interactive tools to quickly identify local conservation areas, listed buildings, protected trees under Tree Preservation Order, and other.
GREEN BUILDING
http://www.energysavingtrust.org.uk/
Consider making your building environmentally friendly, by employing the latest science and technology for sustainable development.
There are some government’s grants to help making houses more energy efficient.
SELF BUILD HOUSES
http://www.selfbuildportal.org.uk/
The portal offers loads of information for beginners and professionals interested in self build sector.