Congratulations on finally getting the plans passed!! I think the councils drag their feet and hope you will give up, sometimes ......
As to what to do - depends if you need the money from the plot for other things firstly. And do you want the hassle of having a house built, and the cost of materials etc .....and then housing market being what it is, maybe it would not sell quickly, or for as much as planned.
Also depends on how much a plot goes for with planning. Can be £100,000 upwards for a little tiny space here. Have just seen two on a prestigious road and they are £550,000 each, and believe it or not have sold, so goodness knows how much the houses will be worth when built!!
Looking at it from a money point of view, I think I would get the plot valued with the planning, and take the money and let someone else have the worry, and expenditure. But thats because I am getting on a bit, and maybe a few years ago, would have done it myself and then sold, but I am more cautious money wise now , for one thing