Two pronged forks were used in many european cultures (including the english) since before the 12th century (I believe) for the carving of meat. Each family might have one of two such carving forks for use at the table. (ie used only to chop up the meat, didn't get anywhere near anyone's mouth.
The earliest evidence of personal eating forks I've come across is in 12th Century Italy (well OK, Venice, since Italy didn't exist yet). Before this time eating utensils were a spoon and a knife.
However, forks were rather slow to take off. By the 14th Century, France had adopted the fork, but England held off adopting these inventions of the hated foreigners until after the time of Henry VIII.
Since it's rather difficult (and probably non-period) to eat without using your fingers with only a knife and a spoon, a serviette (or at a pinch a tea towel) is an extremely useful item, as it prevents getting nasty hard to remove grease stains on your garb from the roast chicken and making the hospitaller angry (if you borrowed the garb).