Just to let you know - I just abandoned my first order for Huel. Not being able to select an alternative delivery address on the shipping page just makes it too difficult - I am not going to send an order with my name on it and the address of the local Sainsbury (nearest DPD pick up point). DPD have not information (except addresses) on their site either.
Suggest you either find a physical retailer or sort this out.
For what it’s worth, I think it’s pretty much standard practice (here in the UK, at least) for most retailers of any product to ship only to the address a card is registered to, or to the PayPal-confirmed address, for security reasons. Shipping to alternative addresses is risky, as it means someone else could fraudulently use your payment sources and have products delivered to them.
Or to a commercial pick-up point where they require 2 forms of ID when you collect the product. And DPD offer that but Hual haven’t integrated it.
You can change your delivery place with DPD once it’s shipped. You can put it to a safe place, neighbour, local shop etc.
@5harpy has hit the nail on the head. DPD offers a host of options once the order has been placed with their in-flight options. It looks like this in the delivery confirmation email 
I really hope this helps you out and makes you reconsider. For what it’s worth you don’t have to have Huel delivered to the billing address (is that what you meant @bigm?), you can choose anywhere you like.
a) you need to actually put that information on your website
b) more mature solutions integrate the alternate delivery choice into their site (it should be trivial - if your web developers tell you it’s too difficult consider getting new developers)
c) consider offering CollectPlus or similar as a paid for option