Disgusting back seat stains and grime

[rufusgti]

The rear seat of our family estate has become so rancid I fear social services may get involved.
Seems to be levels of grease and dried fluids that have left revolting stains. It's never been cleaned, only hoovered. But I need to now attack it with the best cleaner I can.
Is it worth going to Halfords for something specialist or would a household cleaner be better for this. It's an old car so I'm not that concerned about using an aggressive cleaner.
Any recommendations, I'll be sure to post a follow up to show how it worked out.
Cheers