Welcome to the boards BRO.......
My friend and I (We are both 18) went to Europe Backpacking this summer....it was both of ours first real trip traveling in a foreign country alone...we had a great time!!! We went all over Europe in 2 monthes and saw the good, the bad, and the ugly of Europe....you will do the same.....
We were in London a few nights....its a fun place but it is hella expensive....I dont think its a good place to start your trip cause you will burn through your cash like there is no tomorrow....
In Italy, I would reccommend checking out Florence and Rome...they should offer you the good mix of both Enlightening culture during the day and Great clubbing scene during the night......(I will never forget those Super FINE Austrian sisters i met as Amadeus, a chill bar in Florence).........plus in both those cities you shouldnt have too hard a time with the language barrier.....
France is all around awesome....obviously you should check out Paris....but you might also want to make a stop on your way south to Italy in one of the cities in Provence region or along the riviera....perhaps in Aix-en-provence or Nice.......those french women know how to treat a man...their philosophy is "its better to give then to receive
)............
In Greece we went to Corfu an island in the Ionian Sea....we stayed at the infamous hostel THE PINK PALACE....there is tons of info available about this hostel....its a nice place to relax, party, and meet other english speaking young folk...there are tons of American, Canadian, Austrailian, British, and South African backpackers that go here.....its like an all inclusive resort for like 30 Euro a night...(that inculdes breakfast, dinner, nice bathing facilities, 3 person private rooms, a balcony, and use of all the facilities).......you should also check out Athens for a day or two....Crete is a cool island too....in fact, you cant really go wrong with any of the Greek Islands....they are all so beautiful and Mellow!!!!
I would urge you to also consider checking out Prague, Czech Republic seeing as how that was another one of my favorite places, but its kinda outa the way from where you're planning on going.......
If I were you...and i was doing it all over again....I would get the 3 country 6 or 8 day travel select pass from EURAIL for 3 countries......that would be perfect!!! Fly into Paris and start there....then travel down to the south of France.....then over to Florence.......then down to Rome (stopping in Modena where they make Ferraris, of course....and then also stopping in at Pisa, just to see the leaning tower...dont actually stay in Pisa though...its a waste....).........then after Rome take a ferry over to Corfu and stay at the pink palace or go to another Greek Island....then go to Athens Greece for a few nights and then fly via a cheap airline (VIRGIN EXPRESS) from Athens to London....spend 3 or 4 nights in London and then Fly home from London.....
Travel Expenses:
Rail Pass: $300
Air Fare to and From Europe: $650
Easy Jet Air Fare from Athens to London if you book about 4 monthes in advance: $40
Grand Total for barebone travel expenses: about $1000