If you scroll back through this board you'll find loads of meal planning threads and inspiration, it's a popular topic on here 
Personally I meal plan once a week around the weekly delivery of my veg box. I am a bit list-obsessive and keep records of what we already have in the store-cupboards and freezer using the app AnyList, plus right before the veg box arrives I have a quick clear out/review of the fridge, and make a note of anything in there needing used up. Then my meal plan will usually look something like:
- 1-2 meals to use up things which are about to go out of date or off (priority)
- 2-3 meals specifically based around things from the veg box
-1-2 meals that are 'easy' on nights I know we are busy with other activity, usually things from the freezer (I keep a good stock of ready portioned batch cooked meals, or we aren't averse to the odd beige freezer food meals
)
-Remainder specifically requested or 'special' meals e.g. a roast on sunday
Lunches can be planned in as meals but are often things like soup made up from any veg about to go past it's best, leftovers/additional portions of dinners or things like frittata or roast veg salad that are again good for using up additional items.
As I make the meal plan, I cross-reference with my lists of what I already have in stock and the veg box, and make a grocery list on my phone of any additional ingredients we need to purchase on the weekly shop - we try and avoid too many mini 'top-ups' as I find this is a flash point for junk and/or short shelf life items being purchased wasting both money and food! The meal plan itself is just written down on my phone but I have seen cute blackboard/whiteboards for your kitchen where you can write down the week's menu if you'd like to give your family advance warning of what's coming (I often find minimizing opportunities to whinge/negotiate in advance better but that may just be my family )...
This week's meal plan for dinners as an e.g. (bear in mind we are a mixed veggie/non veggie household which complicates things, thats a whole other thread!). Lunches as above will be a mix of homemade carrot and coriander soup made with a glut of veg-box carrots, eggs (omelettes/scrambled eggs etc), sandwiches based off things we already .
Monday: Chicken Kievs/Veggie bakes (from freezer), potato wedges, salad
Tuesday: Spicy Chickpea Stew, some leftover roast chicken from Sunday's roast for meat-eaters if they want it, rice, green veg
Wednesday: Stir-fry with veg, noodles (again leftover chicken if there's any left by then, otherwise can defrost some meat from freezer)
Thursday: Mash, sausages (meat/veggie), frozen peas
Friday: Homemade burgers (meat/veggie), coleslaw, potato wedges or chips
Saturday: Nachos, chilli (will probably batch cook a big batch of meat chilli on saturday, already have several portions of 3 bean veggie chilli in freezer), toppings etc.
Sunday: roast