What representation do you have for the path right now? Just a bitmap?
Typically, you will assign one number to each cardinal direction. Then, you will store the "current direction" of the bot, and work relative to that.
So, if 0 == east, 1 == north, 2 == west and 3 == south on the map, and the robot uses 0 == forward, 1 == left, 2 == U-turn, 3 == right, then you just add the two together and mod by 4 (just mask the two lower bits) to get a "new" direction from an "old" direction plus a turn.
If the robot is going south (3) and turns left (1) then the new direction is ((3+1)&3) == 0 == east.
To generate good instructions for the robot, you need to segment your maze into cells. Each cell should either be "an intersection" or "a straightaway." Then connect the cells in a graph with each of the four cardinal directions either leading to another node, or having NULL in a direction for "here is a wall." Straightaways have two parallel walls; intersections are all other nodes.
Now, solve this maze as a graph, rather than as a bitmap. This should make it very easy to turn the solution directly into instructions for the robot.