My sister made us a GF chocolate wedding cake... mostly out of ground almond - I don't know where she got the recipe though

It wasn't a specifically GF recipe, just happened that way.
If you want to do the fruit cake thing I am sure you have loads of options, as the majority of that is fruit anyway... you could soak the fruit in some fruit juice or syrup instead of alcohol... but beware that it will not last the way that an alcohol loaded cake would.
Doves farm do a really great GF flour and if you use a recipe that involves mixing jam in it can be really great(I do a chocolate marmalade GF cake) The goeyness of the jam seems to make up for the lack of gooey gluten in the flour.. GF flour can sometimes make for a very crumbly, gritty cake.
Health food stores will have plenty of replacement options for milk and butter - not sure about a replacement for eggs.
Finally - you can't please everyone and bare in mind that many allergy sufferers (including me and my MIL) get used to having to go without... just eating the icing...have a piece of shortbread instead, etc, etc. You won't be upsetting anyone, but it would be nice to offer alternatives.
