Bob,
What Nigel said.
I haven't checked on Bell in awhile as I use Rogers, but you should be able to use your iPhone 5 in Europe. However, it MUST be unlocked, which it likely isn't at the present time. If you obtained the phone from Bell, it's likely locked to their network. If you've been with them for awhile, you can ask them what the cost would be to unlock the phone.
As you're travelling "throughout Europe", you might consider getting a travel SIM, which provides consistent rates in most western European countries, and in many cases no need to top-up as billing is post-paid (calls charged to a credit card). The one issue with that approach is that data costs can be expensive, so you'll have to decide whether you want access to cellular data or whether Wi-Fi only will suffice. Have a look at the websites for Roam Simple, Cellular Abroad, Telestial, Mobal, Lebara or EuroBuzz for information and costs.
I've been using a travel SIM for several years, first with a basic "flip phone" and now with an iPhone and it's worked quite well.