Blanc de blanc or blanc de blancs are sparkling white wines made in the traditional style from white grapes alone. Typically a blanc de blancs might be made from chardonnay (the only white grape of the 3 traditional varieties in Champagne), but other grapes may be used in the UK. For instance Camel Valley Brut Cornwall is made with Reichensteiner and Huxelrebe.
These are high acidity zippy wines and if that’s your style here are some well worth seeking out. Those with a cellar door open to the public are shown below.