how to approach for home loan to purchase a flat or any house.
The best and fastest option is to apply with bank that has tied up with the builder. They would handle lot of paperwork within themselves easily.
The second is to finalize the property and then apply in bank directly (do not use any agents - they charge/add their commission without telling you). Bank will help you with all the documents they need from your side as well as the builder/old house owner that are required to process the loan.