If you haven't got time to put in the bid, how are you going to find time to develop the website?
It looks like you are asking for some sort of off-the-shelf, ready-made proposal than you can simply send to the customer. That won't work. A proposal is your suggestions for how to create the site, your estimates of time and cost, and your terms and conditions for doing the work. We can give you general advice for how to write a proposal, but only you can know the details of what it should contain.