Just getting to grips with this new additive.

I've found that Morrison's in a couple of locations has been good on both availability and price of AdBlue (e.g. £11 for a 10 litre bottle, vs the L405's 18 litre tank) and that DIY refill is easy enough once you know what to do.

Getting the first warning light was a bit alarming though as I'd been told by the dealer that refill should be at about 14,000 miles and not the 8,000 or so that my car has done. 2016 SDV8 AB

My light came on at around 10k miles. In the middle of Sardinia with tales of car refusing to start if not replenished. Had visions of abandoned car whilst we walk home
Found some at a local service station and as you say, very easy to refill.

Mine was the 3.0 litre engine so maybe doesn't quite drink as fast as your V8.

see this
http://www.fullfatrr.com/forum/topic39769.html?highlight=add+blue letters not necessarily in the right order