Liase with OV direct for the food. Most cruise lines accepting young children supply food etc. but ask that you get in touch in plenty of time. Give them a call I have always found them helpful. It is also a good idea to talk to the airline. I have not taken a baby with me but those I have met have enjoyed their cruise and the staff always make a fuss of children. There is a childrens tea time ( good opertunity to meet other parents)though the baby is too young to 'go' into the kids clubs. There is a night nursery. The only warning I would give is dont go to the med in the summer during the extreme heat (40f as it is now) as it is difficult to keep a young baby hydrated. Those living in the med ensure their infants are kept in the cool and dont go out in the heat of the day. Doing the same will curtail your sightseeing to mornings. This is no bad thing as you can relax and enjoy the ship. There are lovely wide decks on OV1 and the interior is spacious so pushchairs are no problem. You will either fly to Palma (OV2) or Heraklion (OV1) a 2 or 4 hour flight but both airports are close to the ports and a long drive to southern englissh ports (with an overnight stay) may be worse if not more expensive ! Have a lovely time.
Since the clamp down travelling and baby food has been an issue if you have to fly to where you join the ship but with more and more cruise ships leaving Dover; Harwich and Southampton to name three you might want to consider a UK departure and given that you live in Yorkshire you don't have a long way to go to these ports even if it means an overnight stay before you join the ship.
The above rather rules out a cruise with Ocean Village as I don't think currently they use UK departure ports, mainly all from Palma, which involves flying but hopefully someone will come up with some better options for you.
There is no problem in taking baby food in your main checked in luggage if you are flying. We did this with our son's jars of baby food on several holidays in recent years before he was old enough to eat regular food. It is only hand luggage that you can't take food and drink in, and other restrictions on transporting food are more about fresh food not jars/tins. I saw people making up powdered baby cereals in the morning at breakfast etc. on OV2.
There are high chairs in the restaurants and baby toys in the Base Camp for you to use. There were loads of babies that looked under a year old on the OV2 cruise we were on last week.
I am sure taking a 6 month old would be fine and there are plenty of shaded places to sit and it is nice and cool inside. My son was a bit of a whinger at that age and we found it easier to go self-catering and not have to worry about him crying etc. and disturbing other people. However, if your child is more placid than ours I am sure you would have a great time.