The following macro assumes that the file name which you want with full path is in the current clipboard and will be replaced in the clipboard with the full file name.

For details about the first part of the macro see Run Macro on all files within folder. You have not posted all necessary information to post here the macro which surely works for you.

Replace the second line of the macro with following if you use a project.

FindInFiles ProjFiles "" "" ""

The macro property Continue if a Find with Replace not found or Continue if search string not found must be checked for this macro.

UnixReOff
FindInFiles Recursive "C:\Hsb\" "*" ""
Loop
Find MatchCase Up "Search complete, found "
IfFound
ExitLoop
Else
NextWindow
EndIf
EndLoop
DeleteLine
Top
UnicodeToASCII
Find RegExp "%*^c*$"
IfFound
Copy
EndIf
CloseFile NoSave

Add UnixReOn or PerlReOn (v12+ of UE) at the end of the macro if you do not use UltraEdit style regular expressions by default - see search configuration. Macro command UnixReOff sets the regular expression option to UltraEdit style.