At the start of 2019, the United Kingdom introduced VAT legislation (VAT notice 1003) that requires the sender to pay the VAT on parcels ≤£135 at all times.
So if you are shipping products with a value of less than £135, register via the HMRC website in the United Kingdom. Once you have registered you will be given a number which you can enter in all of DPD label tools after Brexit. More information about these rules you can find here. When you use DPD's online shipping service as a business shipper, you always enter your HMRC number.
Be prepared and register your business with HMRC.