It is actually a very good saving if you buy cheap wine in bulk. As the OP states, you avoid the 288.65 pence tax per litre on every bottle. We "fuelled" our wedding this way; buying one of the various "house" Carrefour Red & White wines and it was excellent value. Decent table wine at a decent price. Think we bought 120 bottles of red and white, at around 5€, before Brexit foot-shooting, so around £450. Imagine the crap we'd have had to put up with if we had spent that much in UK! lol. To further put it into context, we always drink 2€ bottles when self catering in France. I guarantee you won't buy a bad wine. a)the french wouldn't stand for it! b)the cheap wine is either the local vineyards or unlabelled big vineyards c)as per tax comments, we start our wine at £2.20 before taking anything else into the equation, therefore, a 4€ wine over here would be £6 minimum.
I’ve done the trip with Pidou a couple of times and each time I create a basket, I compare each item with Majestic and Calais Wine Superstore. Both times I’ve bought the whole order from Pidou - they have great offers on Prosecco and French wines.
I kitted out my wedding doing this. Paid the corkage fee and bought 150 bottles of wine the a couple of kegs from a local brewery. It was about £500 and we had about 40 bottles of wine left at the end. It was basically a free bar but much cheaper.
Get someone else to drive too as at Calais Wine you can sample every wine prior to purchase :) Compare price to Pidou/Majestic too as some are £1.50 cheaper depending on brand.
eurotunnel day trips to France £25 - *Offer valid for travel between 5th November and 6th December 2018, Monday to Thursday only, excluding Monday 26th November and Monday 3rd December. All bookings must be made before 5th December 2018 The wine is not cheap in Calais Wine