After months of anticipation, they've finally arrived. I have in my hands the new Standard Horizon HX851E.
I've been online to obtain a Licence for my unit and secure my MMSI number by visiting http://licensing.ofcom.org.uk/radiocommunication-licences/ships-radio/
A painless (and cost free task) which took me about 15 minutes, because I actually scanned through the bits that I was ticking the boxes for saying that I accepted the terms and conditions for (don't worry, it's nowhere near as long as i-tunes T&C's).
Just entered the MMSI number into my handset, took another minute or two and that's it done. I'm hot to trot!!