First of all you can do a spectacular buffet cheaply if you want to. I'm going to tell you how I catered for around 400 people of all ages at a golf club a few years ago. (We turned Captain's Day into a family event with the evening presentation.)
Aldi and Lidl in particular will be your friend for deli meats and cheeses. You can make up some gorgeous looking platters and use grapes as a simple dressing. We did meat and cheese together and separately, as well as having trays of crackers. We also put out melba toast with pates.
We avoided sandwiches but did provide baskets of rolls (buttered and plain) for people to assemble what they wanted as they wanted; used French sticks etc to give some variety. Most of it was those part baked bags.
Pint pot tumblers filled with breadsticks/celery and dips as needed.
Melon (skin on and simply sliced) made another simple dessert option. Bowls of fruit also went down very well. Plus salads, just bags of salad, bowls of tomatoes (heritage as it happens because they looked good!) and platters of crudites.
Whole roast joints including a turkey crown formed the centre pieces. These were cold, but looked fab.
Bowls of olives and crisps went down very well. As did a random variety of cupcakes/cakes.
We had some catered sandwiches but literally got the minimum (iirc for 75).
I spent the day before cooking the meats, cooking the sausage and cheese n onion rolls. We also had savoury eggs, pork pies - all that sort of stuff.
Because we were offering a wide range buffet we bought enough items generally for between 25% and 50% of expected numbers to get a portion - except for the meats/cheese/bread.
We dotted everything around the long table and even bar top rather than it being a case of following savoury through dessert. It made things much easier for everyone in a tight space. We made sure that there was a reasonable mix of everything from the buffet within easy reach no matter where you were on the table if that makes sense. Chutneys, pickles, sauces etc were all sort of scattered through it to.
The only thing I would say that we were extravagant on would be that we used all disposable stuff, or had no interest in keeping the pint glasses etc. There was just no way that after catering breakfast and lunch that the evening buffet was going to need anything beyond folks taking stuff home with them or it going in the bin.
You'll need to take into account where you can store the fresh produce safely, I created a list with what we needed/where it needed to be stored/how long it took to prepare etc and made sure that we kept in budget too with it.
Congratulations on your forthcoming wedding!