Lets see a picture of the greenhouse. Can it be heated? What is the roof? How big?

Join a local orchid society. They know your climate issues the best.

It's a standard all glass greenhouse. Heating should not be a problem. My husband can run electricity to it

While electric will definitely be handy, I would run gas to the greenhouse for heating. If that's possible.

Use gas only if vented. I use electric and satisfies my needs. You will need 2 growing areas probably. It might get too hot in the summer and possible in the fall and spring. Glass houses act like a car in the sun. Perfect on cold days. Keep a hi-low thermometer in the glass house. If there is a brand name to the greenhouse call the maker and get advice on too hot in the summer.

You will need to determine the temperature dynamics of the glass house. It might be usable in the summer with a shade cloth.

Bottom line best if highs are low 90's and lows high 40's to low 50's depending on what you grow.

No matter what make sure you have a fan inside. Needs to be on all the time at a low speed. Orchids are air plants. Give them air...

Good luck

Advantages for someone in north Florida growing orchids in a greenhouse: Keeps rain off the leaves.
Prevents wind from knocking over plants.
Able to heat in winter affordably.

Disadvantages:
Temperatures can go well over 100F in summer if you do not provide shade AND ventilation. Plants will dry out quickly.
AND you'll run out of space very soon!!!

How to prevent temperatures from escalating in summer-
Open the door and all vents/windows. Keep fan(s) running 24 hours a day on low/medium speed (depends on fan size comparable to greenhouse size). Put shade cloth over greenhouse all year long. One that is rated at about 60% shade.

If you heat the greenhouse to a minimum of 60F, you will want to grow warm growing orchids - I'll write a brief list below and others can add to it. If you heat your greenhouse to only a minimum of 40F, you can still grow a wide variety of orchids.

Orchids heated at 60F
Phalaenopsis, vandaceous, many dendrobiums but not all, some oncidiums, paphiopedilums and cymbidiums, nearly all cattleya types, and many others. Just ask the nursery you buy from if they'll tolerate temperatures in the 90's.

Orchids heated to 40F
Miniature cymbidiums, most oncidium hybrids and many species, nobile and Australian dendrobiums, Vanda suavis, most cattleya types - especially compact to mini's, many epidendrum species but not popular hybrids and all kinds of interesting things.