If you haven't heard back regarding your enquiry, you can certainly follow up. For general enquiries, Dartford's Planning Department aims to respond within 15 working days but sometimes delays occur due to officer workloads. You can contact them directly through email at planning.admin@dartford.gov.uk.
For specific pre-application enquiries, if you haven't received a confirmation email within 5 working days after submission, it's advisable to reach out to them at the same email address for clarification.
It's always good to ensure your communication is clear and includes all relevant details to help expedite the process.