Hi Toad, since you ask, I recommend the small wine merchant in Ouistreham, on the righthand corner of the street just as you leave the boundary of the ferry port. It really is great VFM, a bottle of very acceptable cidre is about 2 euros for 75cl. Other advice, buy the stuff with the champagne cork and wire, not the rubber stopper, and make sure it's brut (dryish and 4% to 6% abv) not the sec (too sweet and weak at 2%abv). However, there are also a couple of farms that advertise their cidre on the N139/138, but I've never stopped at any. It's also widely available at Carrefour, whom if I'm not very much mistaken, will provide. I suggest you buy a selection of choice ciders and sit in the carpark and try each bottle till you settle on a favourite.
The benefits of cidre are quite clear. It gets you over that horrible conundrum of when you should drink your first beer of the day. It goes beautifully with a full English, it tastes of pure apple juice, and the alcohol is not too "in yer face". It'll have you giggling like a naughty eight year old in no time, then you can segue swiftly back into the tender embrace of Madam Stella without too much wretching.
However, be aware, the full-on Cider Tramp Experience awaits those who over indulge. You should be prepared to start kung-fu fighting with the imaginary giant flying lizards which will be circling your head. Be ready too for the accelerated beard growth, rambling incoherence, yellowing teeth, incontinence and the overwhelming desire to wear three filthy overcoats regardless of the temperature. Your fellow BM members will quickly become tired of your fetid smell and false bonhomee and will recoil from your ceasless proclamations of "yer me best fuggin' mate yer, have a drink, have a drink", spoken in a strange little-heard Celtic dialect, as you thrust under their noses a saliva-riddled, half-drunk bottle of the amber potion. In 1992, I saw an otherwise normal cider-mutated race fan have to be physically restrained from venturing onto the track to berate, argue with and piss on the race-leading Peugeot, because he reckoned it had nicked his bird.
Apart from the diarrhoea, there's not too much to worry about.