Hi
I simply bought some fleece from the pet shop near me and then put some absorbent liners underneath. I think they're actually absorbent bed pad but they work really well and puppy pads would do the job too. The fleece I bought came on a roll and they cut off the amount I wanted which was helpful. I don't know if pet shops near you would have some on a roll but you could look.
You could also buy fleece liners that come with an absorbent layer stitched together. I've heard the GuineaDad ones are good and I'm pretty sure they have pockets for piggies to burrow in too.