Second the VSb opener – bleedin brilliant piece of kit. 4 x AA batteries last over a year as far as i can tell and it works perfectly. The only minor issue is that in the height of summer it gets light so early that your chickens may get let out at about 4am when the foxes will still be around. You can get over this by attaching a simple timer to the VSB which overrides the light sensor in the morning, but not at night.
you can see the opener in this pics of my home made hen house (old garage doors that were hanging around.
Another recommendation is to get a feeder like this:
You can get them off ebay for about £15 but I made this for about £6, including the barrel and a pheasant feeder spring. It takes about 30kg of feed and stops wild birds and rats getting at the food.
Another fox deterent is the electric netting which I think also works brilliantly. My two dogs have both been zapped by it and won't go anywhere neer the fence now! A bit pricey (like the VSB) but it will hold its value really well and you can always sell it on ebay for very little loss.
With this setup (and a very good 35ltr galvanised drinker) we've been able to leave our 6 chickens alone for a couple of weeks at a time with just someone popping in every other day to collect the eggs.