I've been using Halfords anti-freeze in the old car for years. It's an all ally engine with copper rad so needs the correct stuff - modern long life types are said to not be kind to copper.
Needed some as I'd done some work on the cooling system only to find they no longer do the concentrate. Ready mixed only - at about the same price per unit. So now paying near 10 quid for 2.5 litres of water...