The UKHO/RYA electronic chart plotter series has been discontinued.
At the moment there seems to be two replacements out there (to the best of my knowledge)
a) Meridian Chartware EasyCharts (these guys originally wrote the software for UKHO/RYA) : one CD covers UK, Ireland and English Channel £69.95 incl VAT - http://www.meridian-chartware.
b) Belfield Software Chart Plotter: them of the Belfield Tide Plotter fame: they offer same area coverage in a variety of packages with/without Tideplotter on CD, USB stick etc. - http://www.chartsandtides.co.
For smartphone users I have the Navionics Marine app which covers UK, Ireland and Channel for €20 - bargain! Search for it in the iTunes store or Android Market.