If you’re really interested, you might try to purchase a book or two. Please remember that the authors of these books aren’t always designers, so you’ll still need to get the plans modified to be suitable.
What I have noticed is that there seem to be different interpretations of Vastu – what is okay with one expert is not necessarily okay with another. This is not surprising given that Vastu Shastras were refined in different parts of the country in response to the local climatic conditions. What works in Northern India is unlikely to work in the South and vice-versa.
Eventually your layout should reflect your requirements. A ready-made plan can, at best, provide you with a starting point, but no more.