how to find paragraph after the table? Is there is any script available?

There is no carriage return after the table?

That does not matter :-)

The Space After value will be applied:

But what will matter:
Is our OP working with table styles where you could add the value once and all tables where the style is applied will follow?

If not, one has to write a little script to change the spaceAfter property of all tables in the story or in the document.

But that's easy. For all tables in a story, just put the text cursor in the text and run that little ExtendScript (JavaScript) snippet:

app.selection[0].parentStory.tables.everyItem().spaceAfter = "5 mm";

For all tables of all stories* in the document:

app.documents[0].stories.everyItem().tables.everyItem().spaceAfter = "5 mm";

( *tables in footnotes are not affected )

Regards,
Uwe