Cruising the web sometimes uncovers some handy tools. I've just come across The Small Business Mentoring Service's Marketing Plan guide. It isn't just a "fill the blanks" but gives you some guidance as to what should be included in a marketing plan.
Whilst preparing a full marketing plan isn't everyone's cup of tea, it can be a worthwhile exercise for anyone with a great idea, but little idea of how to move forward with it. If you come from a marketing background you may not need the help, but if you don't, you've probably identified marketing as a critical success area - since it's the area that will ensure you get some $$ coming in the door.
Preparing a marketing plan could even be more important than a business plan, which tend to be written without enough practical detail.
Download the Marketing Plan guide here>