I'm off to Norway in Jan for my 50th. Just as well I don't drink 
I'm off to France on a day trip today to stock up on a "Booze Cruise" 
One reason for having an Omega estate, loads of space in the back 
Is it worth it anymore?
Only if you are in easy travelling distance of Dover/Folkestone. When I am in London then yes it is worth it.
I drink a lot of wine.
Day return on the Ferry, £30 or so.
Petrol around another £50
However, one of the wine warehouses does a deal. Spend at least £250 and they email you a code for a free next day trip. So, when you've been once it self perpetuates.
http://www.calaiswine.co.uk/You need to be prepared to buy a lot. But be selective.
This trip I bought Paro Alto Argentinian Malbec and also Jacobs Creek Vermentino. Both around £6 a bottle in the UK, and both really nice, I've tried them before. I paid £2 a bottle. I also bought quite a lot of other more expensive wines, but that's my choice.
Petrol and crossing (if not a free one) £80. Buy at least 30 bottles (6 cases) and you've made back the cost. Then add 5% quality French lager at 11.50 for 24 x 500ml cans and you can soon justify the trip. The absolute minimum saving on UK wine price is around £2 a bottle, usually much more. So it all depends on quantity.
If you smoke, a 30 minute drive up to Belgium, and you certainly justify it. I dont smoke any more, but I used to and my smokes were less than half price.
Oh, I also go shopping in Auchan supermarket for other stuff

One thing. You need a big car, like an Omega Estate !