I would say take it very slowly moving towards veganism.
try to slowly swap fave dishes with vegan alternatives, or find new vegan ones that you can gradually introduce and phase out the old ones.
Some things are easy to give up:
soya yogurt great sub for yogurt
dairy free milk - so many nice options now, and can also be used in place of milk in white sauces, for example
Stock up on dairy free long life milk from the supermarket, get enough for a month or so at a time.
give up all the dairy you are able, but don't sweat if you can't give up everything.
slowly get used to the alternatives e.g. cashew cream is great for a creamy taste in food.
vegan cakes taste fab!
you get the odd half ok vegan cheese, but on the whole, they're not great. but on a pizza with lots of toppings you can't notice the difference.
it does take planning but take the transition slowly - it's getting your head around a new mindset! Find new ways of making favourite dishes. E.g. vegan cauliflower cheese - use a white sauce made with soy milk and add some stock powder for flavour, some breadcrumbs on top for crunch -and it can still taste kid-friendly - this kind of thing.
You can make a vegan "omelette" quickly with chick pea flour.
Curries are easy to make... rice based dishes for kids.
Tofu sausages from Waitrose, linda mccartney sausages / sausage rolls I think are vegan. Potato based dishes e.g. vegan cottage pie are easy to make subbed with vegan ingredients...