First things first:
Welcome to Mercedesshop! You are in good company here! This is by far one of the best MB sites you will find on the web!
Next Cardinal rule: Use the "Search" utility before fielding a question. While all questions are welcome on this forum, many problems have already been addressed in great detail by other forum members...so you may find your answer before you even start a thread!
We have a wide variey of members here with many makes and models, as well as varying degrees of skills with the MB...from those of us who barely know which end of the hammer to use when pulling out spark plugs
, to full-fledged MB Master Technicians!
As rare as the 230E is in the US (the 300E is far more common), I can safely say that a large majority of members on this site owns (or has owned) a W124. So you are in good hands here, and whatever you are getting ready to tackle, we have probably already seen it here!
As far as DIY tasks, it all depends on how bold you care to be. I have tackled repairs I would have never attempted before I joined this forum.
Just realize that "DIY" is a subjective term, and while changing a fuse may be a daunting expedition for one person, changing a head gasket could be a "walk in the park" for another.
Assuming you can hold a screwdriver, own a few metric tools (especially allen sockets and wrenches), I could assure you that with patience, much of what ails your W124 can be rectified in the comfort of your own garage...