I have served 80 quite a few times in my home without catering.
For 10 years I had a New Years brunch for 70 to 85 people. I made ahead and froze rolls and cookie bars a baked han and egg casserole anda fruit dish....either a fresh fruit bown or a hot baked fruit casserole.
I have served a hot BBQ turkey for sandwiches on home made buns....with sides of cole slaw and a mastaciolli salad.
I made a hot turkey dish with sweet and sout sauce and pineapple chunks and a marinated pasta and veggie salad....lots of veggies in that salad....with an assortment of nome made rolls and muffins.
Another party I did oven baked chicken....you know the recipe....rolled in cornflakes. I had 2 friends help on that one. I had 2 ovens full or cooking chicken, and as soon as I put one batch on the table, I refilled the ovens, got done just in time for seconds. I served that with potato salad, cole slaw and those home made rolls again. Dessert was bought angelfood cakes, cut into 3 horizontal slices, layered with custard and sliced strawberries, wrapped and refrigerated over night.
Another time I served a wild rice and ground beef casserole as the main dish.....can't remember what else.
If any of this interests you, say so and I will dig out quantities and recipes.
Linda C

What are the hardest parts to do by yourself?

Keep the food flowing.

I had a couple of parties for ~100 people in my home. Once it was just a regular party - everyone invited to arrive at the same time, the second time it was an open house.

Both times, the most difficult thing was to keep the food table replenished as people ate. Since then, at catered receptions, I've always noticed that it takes about three (ore more) workers to keep serving tables replenished. It's a big job.

So my biggest complaint was that I spent too much time doing that, which took away from my time to socialize with the guests. Thank goodness my MIL helped a great deal with that, which allowed me to relax a little!

You might consider hiring helpers for this purpose, just so that you'll have the opportunity to enjoy your party!

I second what lowspark said, recruit some helpers. They could be at the house doing the last-minute getting ready things while you are enjoying the ceremony. You'll enjoy the party much more, as you should. It sounds like a wonderful event.