Welcome to the community!
What plan do you have -- post-paid or pre-paid? If you have a post-paid plan, it is likely already enrolled for Fido Roam. For a daily fee (24 hours), you have access to your services as you would if you were in Canada. For England, it would be $12 per day (see here). Any use of your services (ie make/receive calls, send text messages, or use data) will incur the daily fee. Note that receiving SMS will not result in charges, however, the data within MMS would be considered roaming data so receiving MMS would incur the fee.
If you wish to use data while roaming, you would need to enable roaming data on your devices. You should note that disabling roaming data does not prevent roaming for voice and messaging.
If you do not wish to use Fido Roam and wish to travel with pay-per-use roaming, you would need to contact customer service to have Fido Roam disabled from your account. The pay-per-use rates for your destination can be found in the above travel link. Alternatively, you might consider sending @FidoSolutions a PM. Once they verify some information, they will also be able to access your account.
If you have a pre-paid plan, those plans are not eligible for Fido Roam. The pay-per-use rates can also be found in the travel link above.
Hope this helps 😀