I'm pro CC / CIO but 7 months is very young still and going from feeding 2 hourly to twice a day seems like a massive change to me, why make it worse by letting him CIO?
Isn't it called weaning?? You need to wean your baby onto food, not starve him and force him to eat. Your HV sounds nuts to me.
Could you try something like, milk feed, 2 hours later solid feed, 2 hours later milk feed, 2 hours later solid feed etc etc. Obviously you do need to give him a bit less milk to encourage him to eat more solids, but you don't want to make it such a drastic change IMO. If he seems hungry before 4 hours since the last feed then give him a reduced amount of milk, more of a milk snack, than a full on feed?
You don't really need to give him a different type of food every 4 hours either, so don't go mad puréeing 1kg of fruit ala Karmel lady. Then when that is working you could try spacing it, so morning milk with breakfast, morning snack, lunch, milk before/after nap, afternoon snack, dinner, milk. Then drop the morning milk feed and ensure afternoon feed is after nap. Then drop the evening feed. Or at least not give it in a bottle by 1 year.
With spoon refuser's, sometimes it works giving them something on the tray to play/hold/touch/chuck, while you sneak spoons of purée in when they are distracted by the things on the tray. Also try introducing spoons into play time?
I've weaned lots of children and I'd say most don't get properly eating vast quantities until 8ish month, before that it's mainly play. Then 9 monthish 3 meal a day and snacks are pretty established with milk 3 times a day (on cereal, in a bottle after afternoon nap and before bed).
Then maybe once you have cracked solids, if he still isn't sleeping well, then you could try sleep training of some kind best suited to your baby. CIO doesn't work on all babies from my experience.
What kind of food are you trying him on?