tamillahh,I agree with all of the points mentioned by MTH (of course). However I have a few specific suggestions relating to "battle grounds".
Could you clarify what type of battle grounds you're most interested in - WW-I, WW-II, Napoleonic War, 100-years War, etc.
You mentioned Caen so I assume WW-II sites are at least part of your interest.
If that's the case, I'd suggest staying in Bayeux rather than Caen. Not only is it a much nicer small town, but staying there presents better options for touring. For a start, you can see the
Bayeux Tapestry which depicts a much earlier battle. There's also an excellent WW-II Museum in Bayeux, and the Gun Batteries at Longues sur Mer are only a short distance outside town (however, I don't know if there are any Buses that go there - I had a rental car).
For the absolute best tours of D-Day sites, I'd highly recommend one of the excellent tours in that area. Some are full-day tours and others can be booked for a half-day. At first glance, they may seem a bit expensive, but I feel they're very good value. Taking one of the tours is by far the best way to get to the most important sites in a reasonable amount of time. Keep in mind that the battle front covered a distance of about 50-miles and extended some distance inland. The Guides know where the most obscure sites are located, so this avoids wasting a lot of travel time. Also, I've found that a tour provides a
much more interesting and rewarding look at the history.
I'm glad to hear that you've ordered a copy of
Europe Through The Back Door. It will answer a lot of your questions and provide good information to help your trip go well.
As you're travelling
this fall, you'll need to get the details sorted fairly quickly. It's a bit unfortunate that you have to fly into and out of London, as that means you'll require both time and money to return there.
I agree that it would be a good idea to skip Greece this time (and possibly also Albania and Croatia, unless you have friends there). Greece is somewhat "distant" from your other stops, which means it would cost both time and money to get there and back. As you're on a tight budget, keep in mind that each change of location will require both time and money.
In addition to the Berner Oberland in Switzerland (which is outside Interlaken in the Lauterbrunnen Valley), you might also consider Lucerne. It's a beautiful smaller city with some nice Pubs and restaurants along the river. If you decide to stay in Gimmelwald, the best option for accommodations would be the famous
Mountain Hostel (it's a great place!). As MTH mentioned, Switzerland can be expensive so you'll need to budget accordingly!
For a route, you might consider London - Berlin - Prague - Vienna - Munich (Oktoberfest) - Spain (Barcelona, Madrid, etc.) - Switzerland - Paris - back to London via EuroStar.
You might also consider adding Salzburg to the list as there are some good "battle sites" in that area, in addition to one of the most beautiful, scenic and historic places I've seen in Europe,
Hallstatt (the town is older than Rome because of the Salt Mines there, and they can be toured). From Salzburg you can take a day trip to Berchtesgaden and visit the
Dokumentation Centre and Bunkers and perhaps the
Eagle's Nest (if it isn't snowed in).
The best method to get from Munich to Spain and Spain to Switzerland is via budget flights. It will be easier to make more specific suggestions once you get your route somewhat "roughed out".
You might also have a look at some country or city-specific Guidebooks, in order to plan your sightseeing, accommodations, etc. in each of the places you'll be visiting.
Good luck with your planning!