sorry you are feeling a bit bad, it can be part of the first week's difficulty. Some people have posted they have felt the same. Take it easy esp getting up, as rushing may make it worse. Take all the shakes you are meant to and drink the water. Try not to do anything too taxing, can be hard if you have others to mind or job etc., but be nice to yourself. If you have any queries ring your chemist, they should give you some helpful advice. I hope it passes soon, most on here said it only last for the first couple of days and then they have no more problems, hope it is the same for you.
Nothing to worry about on the lightheadedness...it seems to be part of the LT journey. Some dont get it, but others do. I suffer from it quite badly but I am always digging or doing something physical in the allotment and I forget and go all hot and faint feeling.
I have learnt to get up very slowly after sleeping as I go all funny as well.
I dont mind, it is just one of those things, but it is a bit strange at first and I didnt really know what was happening.
Like the others said, keep drinking and drinking as this can sometimes cause the lightheads as well...so, just keep hydrated especially in the hot weather.