Croydon Council offers a variety of ways to get rid of your real Christmas tree – with all its lights and decorations removed.
You can cut it up if needed and put it in your garden waste bin (Croydon Council say this service restarted on 14 January, though possibly with delays).
You can take it to one of the recycling centres. This might be the most reliable option.
If you leave it out near the edge of your property (but not in the way) the council should collect it between January 18 and January 31. They warn that if it is not collected you will have to resort to one of the above two options.