I'm considering playing the free to play version of this. I don't play games online so not sure what to expect. What sort of interaction do you have with other players? The few vids I've seen on youtube makes this look just like KoTOR and the like. Where does the online aspect come into it?
You sound like you're in exactly the same position I was in when I started playing as a free-to-play (FTP) a month or so ago. You might want to search the thread for my first handful of posts in it as people gave me some really helpful information here when I was just starting out. Especially regarding some of the keybindings and other practical stuff.
If you enjoyed KOTOR, you'll enjoy SWTOR. That's the bottom line. Being online is irrelevant to that, beyond the fact that you can't savescum (using the Esc key to reset conversations doesn't count... and I only think I've done it once, I swear...
More detail: you can play completely solo if you want, with no group content, and not suffer in terms of story progression or even significant amounts of grinding (I'm now level 44 out of 50 and only just now feeling perhaps one level below where I "should" be, and I'm not massively off levelling up). I haven't even bothered to do any space missions for the cheap XP you get from them beyond the first 3 (you're only allowed 3 per week as FTP anyway).
Group content during most of the story/levelling is essentially in the form of Heroic quests requiring 2 or 4 players and Flashpoints. You'll have to miss these out, but they don't add to the story. Some of Heroic 2 quests can be solo'ed if you're really patient/careful, but I haven't bothered doing them after the first couple of planets as it can get a bit frustrating. There's also dedicated PvP content, but I haven't done any of that.
I'm now level 44, and haven't really treated it as an MMO as opposed to a regular RPG beyond a bit of ad hoc discussion/joking around in General Chat and one or two random groupings here and there. So yeah, you can solo it. It's a lot of fun. The FTP restrictions are slightly irritating in places (esp when a cool purple bit of gear drops and you can't equip it, and having only 2 quickbars which limits the number of abilities you can rapidly access through hotkeys) but it isn't really a problem if you're not interested in post-story/post-lvl50 content.
Having said that, if you do decide to play, and end up choosing the same server (Red Eclipse, the EU PvE server, so you probably will) and wanted to do some group quest content, I'm going to start a second character at some point relatively soon and wouldn't mind doing some grouping for that, without having to feel like I'm holding the group up (because I want to listen/read the dialogue rather than spacebar through the cutscenes) or holding them back ('cos of FTP gear restrictions and because frankly, I'm not a great player). Regardless of whether you want do that, though, do feel free to drop me a line.