Hello & welcome ?
I'm going it (mostly) alone too, don't worry about it, you'll meet plenty of people on a game day and as soon as the games start it's about working together for the objective so you'll naturally become part of the team anyway. I'm finding that now I go regularly there's various other friends who fancy it and tag along to the occasional game too.
Rent for a bit. It'll cost you a bit more for your first few games but it's more than worth it in terms of not rushing in and the amount of knowledge you gain while you sort UKARA.
Public transport won't be an issue if you use your head. Sensible stuff like not travelling in full camo and getting a generic looking rucksack & gun case will mean you're not drawing attention to yourself and what you're carrying - James Bond-esque guitar/cello case anyone?