Both Worldstandards.eu and the IEC maintain pages on the types of sockets in use around the world. The UK uses Type G almost universally (there's the odd exceptions of "Shaver sockets" in bathrooms and some hotels have a strange, round 3 pin setup for lighting only). So you need something that will take your Nowergian C/F plugs and convert them to G. You'll find loads of these in airports, and in fact in stores throughout the UK, as well as plenty to be bought online.
There are a few "tricks" that travellers can use. One is that most portable electronics are USB powered these days, so buying a local (or universal) USB charger can be practical. Another is brining with them a home "power strip"/"extension cable" so they only need one adapter. You can also buy (at a slightly higher price) a variety of "universal adapters" that have different prongs to be extended for different socket types.
Be careful when buying adapters online that they are safe. See if they claim to pass any EU/UK/Other standards. If they run more than one device, they should definitley be fused. Check that the earth is continuous when it arrives if possible (doesn't matter at all for a phone charger, very important for an iron!)