If by "medieval" the question really means the European Middle Ages, say around 1200, then long-distance overland travel is an adventure in itself. How far one could travel overland in two weeks during the Middle Ages depends on several factors: where is the travel taking place; in what season is the travel to take place; and how rich is the traveler.
A fact of life in the European Middle Ages is that there are no paved roads, except the network of Roman roads which where sometimes still usable, mostly in Italy, but, up until the 10th-12th century, also occasionally elsewhere. By and large, overland travel in the Middle Ages would be considered cross-country today. Another fact of life in the European Middle Ages is that overland travel is dangerous and expensive; one should avoid traveling alone, and if one carries any visible merchandise they should expect to pay tolls/customs to the various feudal robber barons en route.
The wise traveler would seek to use water-borne transport whenever possible, even if than means that they must take a detour. Travel by sea or by river boat was much faster and much less dangerous than overland travel.
Where does the travel take place? It's one thing to travel in England or France, another in Italy and a very different one in Russia. Some parts of some European states had reasonably many and reasonably good inns. Others not so much. If the travel takes place along a well-traveled route (say the route from London to York, or from Paris to Rome), then the traveler can expect to sleep in an inn at least two nights out of three; if the travel takes places along a not-so-well-traveled route, then they must be prepared to sleep rough.
The season is extremely important. In those times and places when and where there was real winter travel was very difficult in winter, say from December to March. (From about 1300 to about 1800 England, Scotland, the Netherlands, Germany and central and northern France had real winters with frost and lots of snow.) Spring and autumn rains would transform the unpaved roads into mud pits.
A very rich traveler, or a traveler in the employ of a rich lord could have spare horses, enabling them to cover about 50% longer distance per day than a ordinarily-rich traveler.
Overall, I would say that the expected travel distance per day, in summer, in the good parts of England or France or Germany would be:
Travel on foot, with luggage: 15 km / 9 miles. (75 km / 46 miles per week)
Travel on foot, minimum luggage: 20-22 km / 12.5-14 miles. (100-110 km, 65 miles per week)
Travel on horseback, no spare horse: 30-40 km, 19-25 miles. (150-200 km, 95-125 miles per week)
Travel on horseback, with a spare horse: 40-60 km, 25-37 miles. (200-300 km, 125-185 miles per week)
A well-seasoned traveler could keep this speed for 5 days per week, taking two days off to rest themselves and their horses.
Historically, in the late Middle Ages (end of the 16th century), Spanish infantry was expected to march from Italy to the Low Countries along the well-circulated and quite safe Spanish Road at an average speed of about 23 km/14 miles per day, taking 6 weeks to cover 1000 km (620 miles) from Milan to Flanders. The Wikipedia article lists the time taken by a number of expeditions; the slowest took 60 days (16 km / 10 miles per day on average), while the fastest took 34 days.
