But what kind of fizz?

One of the reasons I don't enjoy Christmas as much as I should is that there are too many decisions to make, especially in the matter of presents. I normally solve the problem by either buying very few, except for close family, and usually at the last moment, or buying none at all.  But the decision making extends into the area of food and drink.  Crisps or no crisps, for example?  They're fattening and addictive, so should we buy them?  Ditto salted nuts, cheese straws (a new find), sausage rolls, and etc.  And so to fizzy wine.  Should we splash out on pukka champagne or stick to Cava and Prosecco?  Reviews in the media suggest splashing out at Christmas but my inherent fiscal conservatism leads me to go for the latter.  Enjoying a bottle of shop bought fizz at £20 or more is something I find hard to do (although, of course, not at all out of the ordinary in a restaurant ).  But this is the time of year when surely, and if you can afford it, it's ok to over-indulge?  Roman Saturnalia anyone?  To Sainsbury's I go and compromise (which is my middle name) by buying a bottle of their own brand champagne that is very well reviewed in the all the right places.  Hope it's ok ...