OpenImageDenoise error: out of memory

So I'm no expert in Blender by any means and I have a bog-standard crappy laptop because I don't really use Blender anymore but I've been asked to do a hefty project for someone.

I'm trying to render out few shots for a sequence and the first shot (despite taking a long time) was done fine with only 1 crash.

The second shot, however, can't get past the first frame without an error saying "OpenImageDenoise error: out of memory"

I've reduced the number of objects, used lower resolution textures etc but I'm still getting the same error. If I switch from CPU in Cycles to GPU it just gets greyed out so I'm not sure that's an option for me.

Does anyone have an idea on how to fix this? My next attempt at a fix is using the PCs at my university but obviously I can't be rendering out for hours at them lol.

Any help is appreciated!

Edit: when first attempting to render, the first frame was fine, however there was something in it I wasn't a fan of so decided to tweak it and restart (lighting issue, had to turn it down). Since then it's been crashing.