Rats in my yurt :0 (

[Sazzaroo]

Hi,
I have discovered rats are coming into the yurt!
I've heard them a few times and after some investigation today I've found some holes in the felt

insulation

and cotton cover.
I think they've got in by coming in between the skirt and outer layer. There are no holes on the outside canvas/pvc outer layer.
At the moment I'm not sure if they are coming in nightly or have decided to make their nest amongst the 3 layers of thick felt.
I'm feeling quite overwhelmed at how to deal with this and would really appreciate some advice.
I am not really up for using poison due to the cummulative impact on wildlife.
I have a cat but she prefers to purr on the bed rather then hunt.
I know they urinate to lead other rats into a space and have found bits of carpet that are saturated. I have cut these bits out and sprayed some mint water around the edges.
I'm wondering if putting metal sheeting in between the trellis and cotton cover would work? Or, would they just dig under it?
Please help I'm feeling out of my depth!
Thank
Sarah