We use-
peas, green beans, sweetcorn, leaf spinach, broccoli, cauliflower, baby carrots, 'mixed veg'- diced carrots, peas, sweetcorn and green beans for DD, 'stir fry' veg. You can also get the steam veg portions, but we haven't had those for a while.
I have also bought today from M&S mediterranean veg and potatoes that you just bung in a roasting tin which look very tasty- height of laziness, but I'm due in Jan, so need the freezer filled with easy to cook stuff.
We used to get mixed peppers too, but they were a bit tasteless compared to fresh.
The great thing about frozen is that you can just get out exactly the right amount- whether you're cooking for 1, 2, or 3, which is economical as there is no waste. It's also really easy to use if you're making a pie or cauliflower cheese, or whatever.
At Sainsbury you can also get a lot of frozen veggies in their own organic range, if you're looking for that- peas, beans, spinach, carrots, mixed veg.
I find frozen broccoli doesn't go mushy if you steam it.