Last April I went on an annual buying trip to Burgundy and Alsace for six days or so. My estate car went almost empty and came back with the axle on the floor. Alsace in particular is fantastic for visiting producers to taste and buy their wines. They are almost without exception set up for visits and so long as you try to avoid lunch (around 12 to 2), Saturday afternoons and Sundays, then you should be fine. For the bigger names it can be worth phoning in advance and checking when they're open for tastings, but to be honest you can nearly always just rock up and get stuck in. Even if you are only half into wine it makes for a great holiday if you are coming from England and have a decent sized car. The channel tunnel is very fast (about half an hour) and you come out the other side straight onto the motorway. If you leave nice and early (get a crossing well before breakfast if you can), you'll be in Alsace by tea-time.
In this last trip I picked up a couple of cases from the highly regarded producer Josmeyer. They're more expensive than most, but boy are they worth it. Amongst other wines I got a case of Les Pierrets Riesling 2002. I had my first bottle this weekend; it was bone dry, intensely mineral and citrus and very long. A really classy drop. In the UK you can buy the 2004 vintage from the Wine Society (but you have to be a member) for £19.50.