That's is an excellent price, I paid over £24 for the same item just 3 months ago - I can confirm there's no filling pipe included - I decanted some into a 10 litre Adblue container I had and used that with the VW/Audi specific filling pipe.
I agree it is an excellent, but taking into consideration my mileage and that the vehicle is due to a service in May next year, I think if I top it up 10l should be sufficient as they will top up the Adblue as part of the service cost.
As it is a 30l tank and after 8000 miles it is down to 36%. Not sure if I have got the maths right, but this indicates I am using about 1 litre of Adblue for 400 miles. In the period between 5th Dec and 17th May we only did 2200 miles so the remaining Adblue should see us through to the next service in May 2024 if my maths is correct. To be on the safe side maybe add 5ltr Adblue in case mileage escalates.
From home to the nearest place that we know of that sells Adblue is a 28 mile round trip. Will wait until we need to pass that way again.