You don't need a table saw to cut a straight line, you can make a circular saw guide(or three) for the cost of a sheet of plywood that works great. Here's one way to make a nice guide done by Jay Bates(he makes very good vids). He mentioned its made for the particular circ saw that does the initial cutting, you also need to use the same model blade( 24 tooth, combo carbide tip, etc.) or you may lose the initial cut line do to different blade thicknesses and/or tooth set.
https://www.youtube.com/watch?v=n-1XKctLrAU
This is just one a zillion ways to do it, lots of other examples on utube. You can buy a guide but these diys are just as good.
Enjoying your build!
Brian