Underlay / Soundproofing for cars

Hello guys,

So, I've found a swimming pool in SWMBO's 2010 Ford Fiesta. Lifted the passenger side carpets and found that the underlay/sound proofing and floor pan beneath was soaking. I've dried the floor out but the underlay is still soaking in patches and smells minging.

I'm considering cutting out the water logged underlay - Only passenger side is affected, rest is bone dry and i cant be fussed removing the centre console to get it out as a one piece.

I was wondering if anyone could recommend a good place online to pick some replacement underlay up from and if there are any particular types or thicknesses I should be looking at?

Cheers