The following should do the trick ( replace semi-colons with commas if necessary)à
Code:
=INDEX('Operator number'!$A$1:$B$35;MATCH(INDEX(Mon!$B$5:$B$39;MATCH(1;Mon!$F$5:$F$39;0));'Operator number'!$A$1:$A$35;0);2)
There is no need to search for the first non-empty cell as long as you use 1.
Beware of the use of merged cells, they will probably get you into trouble later if you wish to do other operations