2nd question.
In the message we received about SD it states:

 Save 20% off postage costs*: Get competitive rates to offer standard and express delivery with Royal Mail and Evri.

I use up to 750g LL which are currently £2.70 if I buy via eBay, and 1k Evri which are £2.94 purchased from eBay. The prices for SD are exactly the same. In fact I can’t see any Option in SD that is ANY cheaper than it is now.