So we need a certificate of lawful development?

Your LDC can be applied for before you start to build which is half the price of a planning application but be prepared in case the response is you need to apply for permission in which case could delay the project by 8 weeks. You can also apply once built but this is the same fee as planning and carries problems if you need to apply for planning as the structure is already there. They cover construction work done on properties regardless of materials used and where positioned. It is not a compulsory document to have either way but is extremely useful in event of disputes and solicitor enquiries. You do not have to have it in place before the builders start but it could save you money in the long run. Regards UK Property Services

This is required if there is some doubt as to whether work will be permitted under planning rules. I cannot imagine why a porch and small conservatory would require this, unless you have a listed building, for example, but if you call your local council planning department, they will certainly correctly advise you. Regards, Paul Albright