Thanks, hopefully this thread is helping a couple of people! The Spirit of Europe tour looks amazing! You are going to have so much fun.
Depending on whether you are flying into London and starting your tour there or if you are starting your tour in Paris I recommend just withdrawing some pounds and some Euro before you head off. It's really hard to get all the different currencies out before hand.
There were two ways I did it one my trip. I found it very easy to just get a decent amount of Euro out before getting to the non euro countries and then in each city/country that doesn't use the Euro it is really easy to find a currency exchange shop and just exchange my euro for the local currency. Alternatively I would just got to an ATM in the countries which didn't use the Euro and just withdraw enough cash for the one/two days from the ATMs. At the start I would exchange my Euro but after a while I would just use the local ATM's and withdraw what I thought was enough money. At most border crossings you have currency exchange places as well so the money that you didn't use you can exchange it to the next countries currency before leaving. I was quite worried about the exchanging of money but it turns out its really not a big hassle at all.
I guess in regards for convenience I recommend just using any local ATMs or exchanging your money at the border crossings before you get into each country. In regards to safety if you were to get out a certain amount of money for each country before the tour then you have to carry all that money around with you before you get to each country and if your bag is stolen/lost then you could lose all that cash. You'll also have to carry all that cash around with you which is pretty risky. I think it is safer to withdraw the money once you get to each country rather than having to carry so much cash with your for the whole tour. Looking at the Spirit of Europe the places you needs different currencies for is later on in your trip which are Hungary, Poland and the Czech Republic.
Reading what I have wrote above seems a bit long winded so to sum up I felt like for safety and conveniences sake it is a lot easier to get a decent amount of pound and euro before the trip and then withdraw however much euro/pound you need as you go. Once you get to places that don't use the Euro then you can exchange some Euro if you have a fair bit left over other wise I found it easier just to withdraw money from the local ATMs. That way you aren't carrying large quantities of cash with you for the whole tour and then exchange those different currencies once you get to the next country.
Another handy tip is that most currency exchange stores don't exchange coins so if you have any left over coins use them on your drive day out of the country to buy some snacks or some little souvenir like a magnet/shot glass as you wont' be able to exchange the coins. I ended up with way too many coins from difference countries at the end of the trip and couldn't exchange them but then ended up keeping them as souvenirs.
Hopefully that makes sense and helps you.
If there is anything else don't hesitate to ask.