Welome to the loony bin, Jo!
I've got no water on my plot either, and had a lovely time last summer lugging watering cans the couple of hundred yards from my house. :x
So.... I sold some old dodo on eBay, and bought a couple of those 1000 litre IBC containers for £35 each (some money, I know, but I bin dived some dodo out of skips and sold it to raise the cash). One is at the back of my shed, collecting rain from the gutters, and the other is on the road side of my plot, at a slightly lower level. The two are connected with hosepipe (out of the school bins!), so the lower one acts as an overflow, hopefully draining into the lane rather than down the back of my shed. The shed one is virtually invisible, as it's covered with some of that hazel twig screening that someone gave me - I'm looking out for some more for the other one, but I've only just got that second one. The beauty of these is, as they hold so much water, there's a good head of pressure (when they're full!), so I can use a hosepipe for watering. I'm also planning on running a spur into the greenhouse for a gravity fed watering system. Lots of people use baths to catch water too round here. Hope this helps!