Mobiles using WAP will be generally cheaper to use for the above services because they will get the information through an Internet server rather than by using the mobile phone networks and some information will be free. Not a latter day Merlin, but a service provided by Transas Marine Ltd using data direct from the Met Office computers. Full details from Transas Ltd . Cost of products depends upon the volume of data provided. The various services offered include weather routing advice although this is probably more use to ships rather than yachts.
Graphical displays are on good looking marine chart format.
The main Met Office site is, of course, open to all and is quite useful.