We had a 90" long table that required a 120" table cloth. I usually found them at Home Goods. But, the best thing to do is to go to a fabric store and buy 3.5 yards of fabric (to allow for hems and shrinkage) and have someone hem the edges if you cannot sew. The fabric store will be able to recommend a seamstress if you need one. Look at home decorating fabrics that are 54" wide as that width will be perfect for a seamless tablecloth. Some home dec fabrics say "dry cleaning recommended" but, I have been washing my home dec tablecloth fabrics all along without any issues. You may find some clothing attire fabrics you like, but check the bolt, because most of them are only 44" wide, which may be too narrow for your table. However, you can ask where their wider fabrics are located and check the out.
Otherwise, you can order tablecloths from many on line sources like: