Carpet, used or new-ish (Old Woking)

I moved home some of the carpets are properly damaged / worn out.
I must replace the carpet in my 5y.o. Child’s room as a priority. Is someone may be replacing their carpet any time soon, where their old one could be a great improvement upon our existing?
The room is a little under 3.5m x 3.5m.
Perhaps
 a larger carpet that’s been destroyed in one area (a corner or along one edge)?
Pics show the sort of marks in his room AFTER a water clean. The burned areas have been melted in various shape (iron, streaks, blobs).
It’s very horrid at present.
I’m able to collect practically any time to suit, ten miles or greater.