There many ways to plan a woodland garden, but here's an easy one.

A lot depends on how much shade you want to create. Planting towering fast growing trees will mean fairly heavy shade in a few years and limit your future pallette to the dense shade growers, That's still a big pallette, but you want to be sure that is what you want because it is a big investment of time and money. Or do you want to do a more part shade woodland garden, with more small trees and shrubs rather than tall trees with big canopies.

The next questions is how wide do you want your woodland to be? Then mark the ultimate borders of that area.

Next lay out your paths, even if it will be years before all of the paths will be enclosed in the woodland. You can do this with spray paint or flour on the ground or with hoses or on graph paper. Leave a "clearing" if you want to put a seating area in.

Now you have the map to begin your landscape planning.

You need to decide how "wild" or how "landscaped" a look you want. In a more planned looking woodland, treat each curve of your path as a bed.

If you have the space outside the canopy of dense shade created by the oaks, you may want to start with some woodland edge small trees as anchors : redbuds and dogwoods are typical.

Add some lower growing shrubs around them like daphne, all spice, summer sweet, osmanthus.

In front of those go the perennials. Hundreds of choices there.

The nice thing is you now have a master plan and can do a "bed" at a time.

If this is a bigger project plan than you have room or effort for, Just consider the oaks as the anchors of two island beds that you connect with a path. Put the tall shrubs either directly around the oaks and then fill in between the shrubs with woodland perennials. Don't forget a few spring ephemerals that will bloom before the oaks leaf out.

One thing to keep in mind for a more wild look, don't repeat plants in a pattern. Do one mass and move on to another type of plant letting the edges overlap and intermix.

Sorry to run off at the mouth and I'm not sure if I'm telling you stuff you already know or helping to at least focus your thoughts.

I'm currently recreating a very narrow woodland edge with a fern walk punctuated with accuba shrubs and some variated solomons seal and a bunch of spring wildflowers I rescued from a builder's clearing. Even though its only 6 feet wide, I still have a curving path done in 2 1/2 foot wide stepping stones. That gave me a placement for the ferns to begin with. Specimen or frangrant plants go right at the end of a curve so a walker is going almost righttowards them.

I planted two wooded lot line gardens, irregular in width, but from 6 to 15 ft wide. In 8 short years, they went from tiny things to full woodland-looking. I have one large tree on each side, east and west sides of my back yard. (one white pine, one swamp oak)
Then filled in with virburnum, low evergreens, River birch, sentinel maples, which are very narrow, pencil juniper, bottlebush buckeye, hosta, ferns. and etc.

It has been so much fun to watch my yard fill in and become more and more private from the neighbors.

Initially, I had soil trucked here and formed into a raised area on east and west sides. Straight edge on the neighbors lot, curved into my yard, which is only 90 ft wide in back.

I planted only 2 smallish trees to the north, because that is my view of the subdivision pond. they really 'frame' the view.

It sounds like you have alot of room to plan a wooded area without damage to well or septic.
There are so many lovely smaller trees out there. Service-berry being one of my favorites. And, if your soil is acidic, laurel, azalea and rhodies.

Just remember to consider your sight lines, sun and light requirements, well and septic systems. I hope you dont plan on planting woodland perennials until your woods has grown about 5 years or so. Keep all of us in the picture. Pondy