Were terms such as "Norman conquest" used by the British historiography in order to deny the fact that they were conquered by the French?

No, the reasons are a bit more complicated and have far more to do with cultural identity in the Middle Ages and the determination of one bastard of a duke.

To describe Normans as French would be like describing Americans as English. They had their own distinct cultural identity different to that of "the French" (which weren't yet their own cultural group, but that's a whole other topic). The Normans spoke a unique dialect of the Old French language, had their own legal system and customs, their own style of architecture, as well as a separate artistic and musical style to other regions of France. This was the product of combining the native Frankish population with the Scandinavian settlers that migrated during and following the settlement of Rollo the Walker, the first Duke of Normandy. There were also behavioural markers of Norman-ness that some contemporary writers identified, such as an attitude of adventurism, a violently competitive aristocracy, strong equestrian skills, and a thirst for conquest. These characteristics were only ever a caricature of course; most Normans, as with every other ethnic/cultural group in Medieval Europe, were farmers who didn't have any of these. It's a caricature - often used as a literary device - that was derived from the actions of William the Conqueror and the conquests of other adventurous Normans like Robert Guiscard, who ruled southern Italy, and Bohemond, who established the Principality of Antioch. Although the average Norman and average Frenchman were probably very similar, at the level of the aristocracy there was definitely a Norman identity among the Frenchness.

To both the Anglo-Saxons and the new Norman rulers, the conquest was a distinctly Norman endeavour; as in an action undertaken by the Duchy of Normandy without the involvement of the wider French nobility. Sources such as The Anglo-Saxon Chronicle and the historian Oderic Vitalis are scathing of the Duke of Normandy who, not content with his duchy, imposed Norman rule over a free kingdom. They held the Duke of Normandy, not France more generally, responsible for the conquest. Some refer to the duke as a vassal of the French king (which he was) but still keep the responsibility for the conquest firmly in William's hands. William of Poitiers, a chaplain for the conqueror, also saw him as acting on his own volition for his own aims and glory (which he sees as a good thing, in contrast to Oderic Vitalis). The French king had not authorised the invasion nor could the French kings exert much influence over England. The fact that a vassal of the French king had effectively gone rogue and made a kingdom of their own led to the development of an intense rivalry between the kings of England and France over who actually got to control Normandy, which frequently led to open warfare. This wasn't France conquering England, it was Normandy breaking away from France. To say that "they were conquered by the French", as you do, completely misses the fact that the French king controlled very little.

So the Anglo-Saxons saw it as a Norman conquest, the Normans saw it as a Norman conquest, and the French saw it as a Norman conquest. Contemporary sources reflect a wide variety of opinions on the conquest of England in 1066, but they can all agree on one thing: it was a Norman conquest.