Congratulations on your new home! If your backyard need the work for safety reason, you may want to check with C&C for rehab loan. I attached the link for you. Good luck and enjoy your home for many years to come!
If you have to do a rehab loan ahead of time, some lenders allow you to extra money to fix up the house based on the future value.
I would do some searches now for pricing for a major yard renovation and get all your costs written down.
Email if you need sources for anything, I have a lot of resources on the island. Or call me. I am on the way to Nanakuli for paddling races for tomorrow!