If a picture message cost 37p that, as far as I'm aware, is the same cost as in the UK. However, you could send a text meaage without turning data on as this doesn't use the data network.
The danger with turning data roaming on temporarily is that anything that syncs in background would be able to do so and you might run up some extra data costs as a result. If Euro Travelller works in Norway, then you could opt in to that your only cost would be £3 per day as usage would come out of your contract allowance (note that most contracts don't include picture messages).
