I tried to paint the fence last summer and it was a disaster!!
First I tried to spray it, like in the "AAAh, hahahahahahahaaaa!!" advert.
Then I tried to brush it out, Like in Karate kid.
Eventually I found the method that works, the "two pole method".
Basically, you get two 6-ft long poles. Put one at the top of the fence, and one at the bottom. The give them paint-brushes and £45 a day.