SOLVED. Boy learns magic through hidden book, and discovers conquering magic empire

[Connor]

Dean CadmanI read this book last year, wasn't old, maybe 3/4 years old.

Starts of with a beggar boy getting the opportunity to help a librarian to catalogue the downstairs store room with his beggar friend, they find a secret room with a magic book inside - this provides the reader with magical abilities - he then uses this ability to create wealth for himself and his friend by collecting gold dust from the river - whilst also enabling them to leave the city in search for other hidden books of magic using the mural on the ceiling as a clue for the next location, whilst stumbling into the mage empire which is ruled by a powerful mage who can take the magics of his lesser mages as his own.

[Connor]

Remembered the series - the Dragon Mage Wars series