Client Request - Builder - general in Castle Cary, Somerset BA7

I wish to replace a garden fence with a wall. The fence currently consists of 24 wooden fence panels(190 x 180) which are beginnng to rot and fall over. I would like to replace the whole fence with some type of wall, possibly rendered blocks, whichever way is cheapest. 14 of the fence panels are around 6ft high, the rest of the fence is only half that height, the wall would need to be around the same height, i.e half of it about 6ft the rest somewhat shorter. The fence is on a slight slope but in a fairly straight line, access is easy, across a lawn to most, going behind a small greenhouse at one point.