Matty, from your profile, you seem like a smart young man! And this IS a good question for me. I love coffee and drink a lot of it. But I also eat healthy, drink plenty of water and healthy drinks, exercise (teach tennis), get plenty of rest, etc. I really doubt that the amount of coffee you are referring to is in anyway harmful...;-)
Almost everything you eat or drink has side effects, coffee included. I don't think only drinking coffee 1-2 a month can cause caffeine withdrawal - a headache- which is probably the largest side effect. Caffeine is a competitive inhibitor for the adenosine recepetor which tells your brain when it is tired.
The caffeine itself has side effects but it only lasts about six hours. Same as if you drink soda, tea or rnergy drinks. For the rest of components, not at all unless you are a real coffee junkie which can lead to liver problems, specially with the commercial coffees you get in the US