Although I'm not in your neck of the woods, your contract may or may not clearly state breach and or cancellation procedures as well as remedies. Are you represented by a Realtor? They should be able to answer your question. If you do not have a Realtor, consider speaking to one that can give you a run down of the norms for your area.
The simple answer to your question is yes.... you can cancel. The hard part to answer is when. Your contract has parts to it that allow you to walk away if certain things aren't met. For ex.... If you can't secure a loan you can cancel. If they refuse to make repairs according to your contract you may be able to cancel. The answer is in the contract.
I would hope if you submitted an offer you plan to see it through to completion. There are some unforeseen circumstances sometimes that may cause you to withdraw an offer.
It is normal to feel what we Realtors refer to as â€œBuyers Remorseâ€ This happen a lot when you have rented and suddenly you realize that you are now responsible for the total up keep of the home. This thought wake some people up in the middle of the night.
There are warranties and insurance company set up to help you.