All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If the entity responsible for granting you the money agrees to give you this money before you start studying, then there is nothing wrong with taking it and benefiting from it because this matter is determined by that entity. The important thing is that the applicant does not lie in the application and provide false information in order to receive the student grant. It was narrated that the Prophet said: “The Muslims are bound by their conditions.” [Abu Daawood, An-Nasaa’i, At-Tirmithi and Ibn Maajah]
Abu Hurayrah narrated that the Prophet said: “He who cheats does not belong to me (is not one of my followers).” [Muslim] He also said: “Whoever cheats us is not one of us, and cunning and deceit are in Hellfire.” [At-Tabraani] This applies to all forms of cheating, fraud, and plotting in any field and against any person, as is clearly understood from the (general) wording of the Hadeeth.
If a person adheres to honesty and truthfulness, and the concerned entity approved his application and granted him the funding before he starts studying, then there is nothing wrong with that.
Allah Knows best.