Lidl were doing one of their 'specials' recently on Petronas oil, supplying it in 1 litre containers of various viscosities.. Not sure of the grade or the API spec, but may be worth calling in...but you may well get the same oil in the correct grade elsewhere for less in 5 litre containers.
I'm sure you are aware of the importance of the correct spec of oil for your car; not just the viscosity but the API rating too. Gone are the days of just 'bunging' anything in!
As regards AGM batteries, some vehicles require replacement AGM batteries to be programmed to the car, using the QR code; basically so that the car 'knows' it has a new battery relative to the now different state of charge.
Sounds ridiculous, but there you have it....
There are EFB batteries which are a cheaper alternative to AGM batteries, and they are also suitable for Stop/ Start vehicles. Honda fit them as OEM equipment.