My car's been sat on the drive for about 2 weeks. Treated it to a wash the other day though!
How often does aircon need to be regassed? I take it it depends how much you use it? Mine's a year old but I've only used it a couple of times (including a 5 hour drive across the country on what was the hottest day of the year so far).
Don't know about the parts numbers but looking at pictures online I can't see any honeycomb grilles that have chrome surrounds. The Zetec S and ST both seem to have the same grille, with the others having the chrome bars.
It's probably the £60 one but they should both fit.