TheDibb is another amazing source of information regarding holiday planning, as well as Its Orlando Time previously mentioned. Check out FrugalBrit on Youtube - he has good info.
You can do Orlando (Florida is probably bigger then the UK) without a car, there is the iTrolley and ubers etc. If you get your KSC tickets from attraction tickets you can get transport included.
Food in Disney is extortionate, I haven't had the pleasure of Universal yet, but I suspect its the same.
If you go to the Seaworlds (Bush SeaWorld and Aquatica) you can get an all day meal deal which was ok.
Discovery Cove has Inclusive dining but closes approx 17:00 - That is a paradise and I am going back in late Nov :D
You can get Ubers to Walmart and the Malls easily enough.
For Disney - if you are only going once, it might be worth factoring in the Paid for Queue system - either Genie Plus ($15pp pd) or Lightning Lane. ($4-15 pp per ride)
June is really starting to get hot, so if you do go, make sure you get a hopper so you can visit the 2 Disney Water Parks as well - Typhoon Lagoon and Blizzard Beach.
Depending where you stay you can get shuttles to the park and Disney hotels.
Sorry for the long post, am not an expert and I have only been twice, but currently planning another trip later this year.