Keep looking, especially on the internet websites. People who find cats may only look on the day they find them then not bother again so it's vital to recheck and repost his details.
Please don't give up hope, it's only a week, there's a good chance he's shut in a shed or house where the owners have gone away for a few days. If you post flyers at the school gates, the local pub, railway station, job centre... saturate the area.
Try Gumtree. I dislike that site immensely but folk do post lost and found animals on there not knowing where else to go.
You say you've tried the local council, make sure they have a picture of him, if the warden knows he's missing they will be alert.
Keep us posted on here, repost to this page daily, and you could consider changing the title of this post to include your area so if anyone googles the term "ginger white cat lost found Oldham, Manchester " yours will be the first hit they get.
I'm very sorry your precious boy is missing. I hope he's safe and well wherever he is.