Is it better to get Pounds and Euros at the London Airport or to get Euros at the train station in Paris?

Its better to change your USD to pounds in London and change USD to euro in Paris. Changing USD to euro in london will be more expensive than doing it in paris. When you get off the train in Paris Gare Du Nord, you can change dollars to euros.

Airports are notorious for giving bad exchange rates. I think your best bet is to go into a town and go to a bank since some banks in the UK take no money from you when exchanging. If not then the train station in Paris will probably be better for you.

Yeah if possible try and use your card and take cash out from one of the high street bank (like HSBC, Citibank, Natwest etc) cash machines - you'll get a much better rate. Try and change some pounds (or dollars) into Euros before you get on the train - earlier this year I was at Paris Nord and the line up at the cash machines was terrible, I also tried to change some pounds to Euro's and the exchange rate was awful. The lesson learned was make sure you've got some Euros before you get to the station!

If you have an ATM card that's the best way to get your money. You will generally get a better exchange rate, but watch out for user fees. You don't want to be running to the ATM every day. Try to estimate how much you'll need and then get enough for several days to keep your fees down. Carry the money somewhere safe, like in a passport pouch you wear under your clothes. Pickpockets are very common in both London and Paris. If you don't have an ATM card you are probably better off exchanging money at a bank or an exchange facility that is away from the airport or train station. You usually get the lowest rates at points of entry into a country (stations and airports). In any case, wait until you get to France to get your Euros.

The exchange rate fron USD to pounds or euros will smite you. You will want to get just a bit at the airport. Say 150 pounds and say the same in Euros. You will pay much but you need to have pocket money. Here is the thing though. Call you bank before you go and inform them that you will be traveling as otherwise they may shut your card down. If you use a credit card it may cost much. A debit card (w. a Visa logo) though may only cost $10.00 each time you take money out. So you take a big chunck out when you do rather than spending $50.00 each time you exchange money.

Go to the Post office between the airport and the train station? They have good rates!