Given your interests, you may find the SE Complete Bundle to be enough for your needs. Even with SE, you will find that you have a much higher finished sound quality than with GPO and the like (I was a GPO user back in the day myself).
The other thing to consider getting is VI Pro. VI Pro adds a great deal of flexibility to the free VI player, and the "stretch" function can be used to create additional articulations that will help fill in the gaps of what is offered in SE. There are many other advantages in VI Pro as well. Generally, it is suggested to master the free VI first, and then upgrade to VI Pro.
The SE libraries do require far less computer power and less ram. SE 1, 1 Plus, 2, and 2 Plus combined will fit quite nicely into a mere 8 gigs of ram.
One advantage with VSL is their discount structure. If you do start with SE Bundle and later decide to go to the full Cube, your Cube price will be discounted.
Like you, my interests are at the hobby level, though more traditional symphonic/chamber than pop-orchestral. In the VSL world, I started with SE - the old version of 1, 1 Plus, 2 and 2 Plus. I then went to a mix of full libraries + SE, and recently to the full Cube. There is no question that I prefer the full Cube, even though I am a bit limited due to my computer specs.
If your budget is tight, I would suggest starting with SE. If you could afford it, going directly to the Cube would be strongly worth considering. Running the Cube requires far more computer power, and ram. You don't list your computer specs, but having 32 gigs of ram for the whole cube would be strrongly suggested.
Last, one of the biggest differences for me between SE and the full libraries is the percussion in SE vs. the full library percussion. There is a wealth of percussion in the full library (standard + extended) that is simply not available in SE.