Following because I'm having exactly the same thoughts about my 10mo's lunches.
I was thinking of getting a good cool bag (one of the ones with ice packs) and sending him into nursery with yoghurt, fruit purée (for on top of yoghurt - he is obsessed with yoghurt), cheese cubes, chopped up fruit and veg (chopped blueberries, grapes etc., carrot and cucumber sticks), maybe sausage rolls, pasta, dry Cheerios, and some of those prepacked wafers/Organix crisps as snacks. You can use puff pastry to make sausage rolls, spinach and ricotta rolls, pinwheels which can all be served cold. I've been batch cooking things like meatballs and putting them in the freezer. They could be chopped up for your DS.
DS has three teeth now but even before he got them he was surprisingly competent at chewing most things.
I'm also sending in breakfast. I'll be sending the Organix baby porridge (which is really nice imo but Ready Brek is also good), Organix baby cereal and milk. Grown up porridge is good for filling them up but probably too much effort for them to make at our nursery - I bought an insulated baby food container in Boots but an ordinary Thermos (the ones for food) would keep the heat in.
I think if you toss avocado and apple in a little bit of lemon juice they won't discolour so much?