My mate hasn't got enough mature media to donate but he says I can squeeze his sponge out and add the contents to my tank. Would this help or just be a waste of time? Thanks

Depending on what sort of filter you have, and if your friend has a spare plug socket, could you run your filter in his tank for a while? That's how I matured the Fluval 3 for my 12 gal. I stuck it in my mature 30 gal community tank for 2 months.