Hi Jazib,
As standard when you execute tcode TP01 it will default the personnel number that is assigned to the user. You can control the authorisation for this in your role for object F_TRAVL. I think in the personnel number check object AUTHP you need a value E.
Also look at this link which explains the different authisation objects in travel planning.
http://help.sap.com/saphelp_46c/helpdata/en/ba/d48438ad5ff84ce10000009b38f842/content.htm
Hope this helps
Ankur