You can submit a planning application online. Every LPA in England can be applied to using the Planning Portal. If you are working without a planning consultant, then at the start of the project you should check to see if your project requires planning permission, building regulations approval, or both.
When submitting a planning application, it is worth noting that online planning application submission requires a planning fee of at least (subject to your development) £60 to be paid as part of the application process. The application will not be submitted to the LPA without payment of the planning fee.