I want to know if I can interface Craft address details into DPD shipping site New to this and just looking at a few solutions for a small start-up. Would I be able to take address details directly from Craft and interface directly to preferred carrier which is DPD here in UK? Currently my customer is typing address details from existing e-commerce site into DPD !!!
Probably depends on exactly what you're looking to do, but it does look like DPD has some APIs you can integrate with: https://www.dpd.com/nl_en/business_customers/help_en_tools/labelprint_tools/dpd_integration_services

Assuming that's the case, you'd be able to write a Craft/Commerce plugin to pull the data out that you need and interface with their APIs.