You can also buy IBCs with galvanised sides, which is pretty cool. They can be £10-20 more expensive, but makes the whole thing more robust, in my opinion.

Eg: smithsofthedean.co.uk/…/ibc-tank-1000-litre-galva…

Ours have little holes drilled in the front side every 100l to expose the plastic tank underneath, so you can see the liquid level.

I would recommend this type so you don’t need a separate cover, which could get ripped etc.