If you are planning a new woodland of more than two hectares, your planting comes under the Environmental Impact Assessment (EIA) regulations for Forestry. You should consult the Forestry Commission before starting any planting on the ground. Then an 'Opinion' will be required from the Forestry Commission as as to whether formal 'Consent' is needed.
Formal consent, including an environmental statement, is usually only required for large schemes over twenty hectares. The Forestry Commission will consult at the 'Opinion' stage with relevant organisations and can arrange a screening meeting if there are issues that need addressing. This is normally done as part of a new planting grant application.