This type of situation probably needs some inference in order for the asker to understand the answer.
"Ahead, further on, on, further" are all valid options if you can refer to the path the asker is currently takingare referring to the path the asker is currently taking, since they all imply "more"/"continuing as you are".
In the event that you can't direct the asker in that mannercan't direct the asker in that manner, then your suggestions aren't so good, and you would need to be more specific in your response:
You're close. It's about 200 metres that way points in the appropriate direction
Does that answer your question?