I don't see you having much catching up to do. I missed all of the RCT stuff but I've been working on PC nearly constantly for 2 years. And you're already leaving all I've done in the dust
Cool that You are inspired by a park which is literally 30 minutes from my place! I would say good start. Especially your layout is already very good
Looks good so far. The big difference between PC and RCT3 is that in RCT3, it's much easier and quicker to build nice looking and highly detailed parks due to all the cs available. With PC, you literally have to make the "cs" yourself for nearly everything. So it takes so much longer to get the park in a finished state. The nice thing in PC is that it is so easy to add tons of details wherever you want, instead of objects being stuck on a grid as it is in RCT3. So you can add and add and add until your heart's content. You'll just need more patience and practice to learn all the tricks to help speed up the process.
In the park, I completed the restaurant building:It's massive considered it's just a small park, and it's a good lesson for future planning phases, but for now I kept it as large as it is.Needless to say, it has a lot of empty space inside.