The easiest way to reach Green Timbers Urban Forest from Surrey is by car. A free parking lot sits off 100 Avenue between 144 Street and 148 Street. Transit also works, but the bus you need depends on where in Surrey you start, so plan that part with the TransLink trip planner.
Parking off 100 Avenue
The main lot for the forest is in the 14600 block of 100 Avenue, and parking there is free. If you would rather begin at the Surrey Nature Centre, its address is 14225 Green Timbers Way. From the nature centre it is roughly a 10 to 15 minute walk along a forest trail to the lot, so the two make a natural pair if you want a longer loop. There is also some parking along 144 Street just north of 100 Avenue.
Road projects have been proposed around the forest, including changes to 100 Avenue, so check the City of Surrey website for current closures or detours before you head out. Type the street address into your map app, since the park name alone can send you to the wrong edge of the forest.
Reaching the forest by bus from your part of Surrey
The Surrey Nature Centre can be reached by bus, and that is the easiest transit target to use. Open the TransLink trip planner, enter your starting address and set the destination to the nature centre or to the forest itself. The planner lists the route, the stop and the walking distance from it, and it shows the last departure home. Check it on the day you travel, because routes and timings change.
If your trip starts at a SkyTrain station, the planner will also tell you where to transfer. Do not rely on a route written down months ago.
Walking in from nearby streets
The nature centre connects to the rest of the forest by trail, so anyone living within walking distance can arrive on foot and skip the parking question. Bring a map or save an offline copy, since the trails branch in several places.
A taxi to the Green Timbers lot
A taxi is handy when you carry a stroller or gear, or when the bus transfers do not suit you. The Vancouver area taxi page covers service in the region, and the taxi fare estimator gives a rough idea of the fare before you book. Give the driver the 100 Avenue lot or the nature centre address as the drop off point, and book the ride back before you head into the trees.