The following worked fine for me
UK, prepaid Micro sim, carrier = 3, 10 pounds 1 month, 1 GB. You can top it up on next trip
Norway, prepaid Micro sim, 100 NOK (usd 18), Telenor, you get charged 10 NOK for each day you use data. Must show passport to buy.
El Salvador, Prepaid SIM, cut it using...