Hi there
I’m new to beekeeping so please bear with!
I’ve just purchased the: Flow Hive 2+ Cedar 7 Frame however my NUC is coming on Hoffman National frames.
Is it an easy job to make them fit? The same as this: Link
Thank you
Hello and welcome to the Flow forum! 
I have no personal experience of adapting Hoffman-style National frames, but having looked up the measurements, it should work just like the link you posted, as long as they are not extra deep (14x12" or jumbo) frames. Nuclei in the UK don’t commonly use those frames sizes, so you should be fine. 