I do love the fact men think when you're at home all day you're sitting around watching day time TV, in your PJs, eating cake and drinking loads of cups of tea. THAT WILL NEVER HAPPEN AGAIN once you have children (OK maybe when they're 16/18/21!)
Looking after a 6 month old is time consuming. When you're not milk feeding you're weaning, getting them to sleep, getting them dressed/washed/creamed, changing their bum, washing up their bowls & spoons and turning the bomb site back into your dining area, refreshing the stuff in the change bag, emptying pooey bins, washing clothes, hanging them up, ironing them, cleaning the house, preparing their next meal/activity etc. And all that is as well as keeping them safe, happy, playing with them, teaching them things etc! Yep. You've got loads of time to prepare meals for him! I would ask your DH when do I get time off?
I'm lucky as my DH does nappies, baths and cooks all our meals and prepares all our DDs meals which are frozen and I just defrost. In turn I look after her all day and once she's in bed I get my night until the dream feed. I do the cleaning, washing, ironing and household budgeting in my 'free time' so not all night to myself! Also my DH and I take it in turns to go into her if she wakes in the night so one of us always gets a better nights sleep than the other each night so we're not both frazzled or more likely I'm not completely frazzled!
My DD doesn't nap that much during the day so I'm always on duty and never get much chance to prepare things during the day. In her morning nap I have a shower and breakfast then at lunch I make lunch and clear up her lunch stuff then she's pretty much up again! Tell your DH he's had it good so far and to start pulling his weight. It's his child too and it doesn't sound like his life has changed that much since becoming a parent. It should have done.