A pass would be a very good idea for your trip in my opinion : you get full flexibility in the UK, Switzerland, Germany and others while last-minute tickets are very expensive. Simply log the train on the app before boarding, hop on and that's it!

A 3 months pass might not be needed as tickets are really cheap in Eastern Europe.

Be aware of the mandatory reservations on Eurostar and French fast/high-speed trains though. Some need to be booked well in advance (especially Eurostar with a passholder quota). More info : https://www.seat61.com/interrail-and-eurail-reservations.htm

Greece and the Balkans in general do not have international trains. Either take a bus from Sofia to Thessaloniki or take a ferry from Italy.

make a coarse plan for your route. count the traveldays. since it will be pretty sure a lot, an interrail global pass will be a good choice. if you move only every 4th day, 15d in 2M and separate tickets in balkans will be an option. but when you move like every 1.5th day, pretty sure a 3M continuous pass will still be the best deal even if you have to buy bus ticket sometimes in Balkans..

You can see prices for many of those trains on Trainline. At least as far as Switzerland, and onwards to Austria and your international train to Budapest.

(I don’t necessarily recommend you buy from Trainline, but it’s a great place to quickly see prices.)

For Hungary to Greece & Croatia, you’ll have to check the individual train operator sites. I would also see this page of Seat61 (and the whole website in general) for details on possible routes to Greece + prices.

https://www.seat61.com/Greece.htm#london-to-athens-by-train-via-belgrade

But I think you will definitely get good value out of a pass as far as Austria. Beyond that, train prices are relatively low, and you might be better buying tickets instead.

Thanks! I do know that I’m going to spend extended periods of time in about 5 of those places. I was wondering the most effective ways to travel in areas like Scotish Highlands, North and South France...Also, I’m flying home from Edinburg, Scotland, but I’ll coming from Greece, so I’ll need plenty of time to get back to get that flight. Part of me thinks hitching in certain areas would be effective. Thanks everyone!