I wouldn't use JP Chenet to deglaze a shitty toilet bowl. Bottle, box or otherwise. Absolute monkey piss.
Shiraz is quite alcoholic - usually 14% or more - so not great for hangovers. The extra 1 or 2% makes a big big difference.
I'm after a single or double varietal - ie made from one/two grape types, or three at most. Tempranillo or a Montepulciano preferably. 12.5% ish alcohol. Clean, single variety, relatively light. I know from experience at Glasto that the cheapo blends like "Spanish red" can lead to diabolical hangovers. God knows what leftover shit they put in there.
One of these. I think I'll fork out the extra few quid for the Tempranillo. Tesco and Morrisons don't seem to have a good offering at the moment.
Although that said, I drank 3-4 different wines last year, including from the wine bars and got no hangovers so who knows.