The bank issuing the card ("your bank") has a daily withdrawal limit.
On the other hand, the operator of the ATM (usually a local bank), places limits on maximum single withdrawals in order to make cash machines less likely to run out of cash by a few big withdrawals (my Maestro card 's got a daily withdrawal limit of �1500). The biggest single withdrawal I've been able to make in England has to be around 700 GBP and, AFAIK, it's from the only bank whose ATMs are prepared to give you anything over 500.

When I was a student living in London a few years ago, I didn't bring any traveler's checks. Just completely forgot.

I can't speak to the cost-efficiency of these options, but as far as convenience, I used my credit card and ATM the entire time, even traveling to the Continent. In Paris I found a few ATMs that wouldn't take my card (not on the right network) but always eventually found one that would work.

One of the biggest advantages of traveler's checks is that they seem relatively easy to replace. I had a friend whose checks were stolen, and he just went to the nearest Amex office and got replacements. Total time spent: about 1 hour. On the other hand, if you lose your credit or ATM card, I would imagine they're not nearly as easy to replace.

If you do use the local bank machine option, it wouldn't hurt to carry bank cards from two different banks. The first time I tried to use a European bank machine with my Canadian debit card (at CDG), I got an "unable to complete transaction" message. Tried again with the same card and got the same message. I walked away, but turned around, and saw somebody successfully using that same bank machine.....so I went back and tried yet again, this time using the debit card of a different Canadian bank. It worked. Both bank cards and the bank machine were connected to the same network....go figure. The card that worked was from a big name bank....the card that didn't was from a smaller bank....that might make a difference too.

-Notam