Hey Arion, WELCOME TO THE BOARDS!
Well, I guess you can start with your interest. What kinds of things are you interested in? This can help you dictate on how to plan your route.
For example, if you like castles, beer, skiing, beaches, ancient ruins, sex and drugs, history, etc...
castles and beer = Germany, Scotland, Ireland
Skiing = Switzerland or Austria
beaches = Spain, Italy, Greece, Southern France,
Sex and Drugs = Amsterdam (really anywhere)
ancient Ruins = Italy, Greece
history and architecture = All over
museums= France, Spain, UK, Italy
Make sense? Since you'll only have six weeks, zero in on your interest and then plan a transportation route that would make the most sense to maximize your time and save you money.
From Ireland, knock out the UK, then head to Amsterdam and work your way down to France, skidaddle on over to Germany, hit up Prague, work your way through Austria, then to Budapest or any other Eastern European countries, amble on in to Italy, head west through southern France and mozy on down to Spain and Portugal and then make your way back up to Ireland(if you're flying outta there. If you follow that route, you'll be making a big circle(more or less) without much backtracking.
As far as preparation with your gear, check out the
section on backpacks and money belts, and read the pages on
tips, and the section on
packing. These pages should address some of your concerns and help you in your preparations.
Hope it helps!