I have a loverly loaf of bread, textures, shaded the lot but it's to be part of a much bigger scene. When I export it as any of the files types on offer in the drop down, 3ds. .abc etc., the shader nodes don't come with it and I'm left looking at something like a plastic lump. Do I have to redo all the shading/textures/normal maps etc., in the scene to which I have imported the object or is there a way to bring everything across? Also tried the append function and had no joy.
From blender it is possible to link to an asset that is in another blend file. No need export/import for this. Check in the file menu under link/append.
Be aware that there is a difference between linking and appending. With linking you cannot change the linked data locally (as it will still be loaded from the original blend-file). The benefit of linking is that you can change the object/material in the original file and it will be automatic updated in all scenes where it is linked to.
Before linking works with an object. also be sure this object is in a group. And you link the group in stead of the object. Otherwise you won't be able to move the object.
By using append you will be able to change the data as a copy will be stored in the blend file you are working on. (more similar to Copy paste).
You should not use the import/export tools when copying stuff from one scene to another. Use the Append tool in your big scene (File->Append) and choose the bread .blend file. Then navigate to the "Objects" folder in the .blend file and select all objects belonging to your loaf of bread. This will import it with all materials applied.
The alternative is to first open the bread .blend, select the bread and press
Ctrl + C and then paste it into an other file opened with
Ctrl + v