Nothing easier to make yourself than guac. Depends on how you like yours but I use: ripe Haas avocados, salt, minced onion, chopped chilies, fresh lime juice. 5 ingredients - easy peasy! Some people like chopped tomato in theirs. Some people like simply avocado, salt & lime.
Lupe Pintos is great - only wish I had one local to me!
I am the queen of guacamole purism!

I use ONLY garlic salt in mine, and everyone that tastes it seems to love it.
The problem here is finding avocados ripe enough. Even the ones that are labelled 'ripe and ready' are still several days away from perfection for me, so i have to plan my guacamole fixes like a week in advance.
Yes the Mexican food is crap here, but it is getting better slowly... Kate, we have at least 3 burrito places in town now (Taco Mazama, Pinto), and their food is really nice, although maybe different from what you're used to. Another Mex restaurant has opened on the South Side and gets great reviews (i think it's called Nachos?), but we've not been yet. When you get used to the curries (especially in Yadgar and Karahi Palace), you kind of get over the lack of Mexican... at least, that's what happened to me!) I live near Lupe Pintos, so generally just get the stuff and make my own.
BTW, I'm from California and have lived in the UK (mainly in Glasgow, but a few other places as well) since 1985... so, Hiya!