Link 1: Planning Finder

Planningfinder.co.uk is your portal to planning applications across the United Kingdom. We bring together commercial and domestic planning applications from all council authorities to provide you with simple, accessible information about planning applications in your area and by registering your details, we can send you an email whenever a planning application is submitted close to your registered postcode.
PlanningFinder works by searching for applications on local authorities' websites and then calculates which ones are close to you...
Note: Some local authorities are not covered by Planning Finder. Link to check those that are covered:

Link 2: Planning Finder Coverage