My DD is gf. It was an epic pain to begin with, but we are now completely in the swing of things.
I tend not to buy many of the products that try to replicate gluten-containing foods, as by and large I don't think they do a very good job of passing (but as a pp says, likely you would get used to them).
However, there are loads of alternatives that are naturally gf and delicious. Nigella's chocolate olive oil cake is amazing, and is naturally gf and also dairy free (and no way do you miss either). Breakfast pancakes made with banana, egg and baking powder are really yummy (with a light sprinkle of sugar on, they taste like a cross between proper pancakes and French toast).
Gf pastas are usually not bad at all. We like the Waitrose one, which is made with corn and rice. M&S are starting to do quite a lot of gf foods. Their gf breadcrumbed chicken and fish are good, so are Waitrose.
The main problem comes with lunch. We get through a lot of corn cracker and oat cakes, but neither have the weight of real bread, so we tend to bulk out calories with other stuff.
Eating out is becoming easier and easier. Some dishes are naturally gluten free, but nearly everywhere does gf options now.
I know the diagnosis is a shock, but you and she will quickly adjust.