Templates are a major time_saver: The most obvious benefit of using a template is that it's a major time_saver. You don't have to create everything from scratch because a lot of the complex work is done fore you. A template allows you to drop in the look you want and then customise according to your needs. This is significantly faster than starting from a blank canvas. Templates can give you a competitive advantage: When you manage projects and delivery it successfully, it's essentially competing with other project managers, departments or against another company.
You can look online for sample proposals that you can work from, in many cases you will be able to download a template that you can work from. You will most likely find that there are dozens of sites offering hundreds of different templates to download. It may take a while, but you will find that there proposal forms that will match almost any need including yours. Take your time and select the one that best suits your needs.