care base and drianage

I have searched Google and am now more confused than ever.I park my car in the front garden on grass, not ideal when it rains, so want to make concrete base to park the car on.The size pf the base will be 3 meters x 4 meters.I think the mix should be 1 : 5 and it seems the base should be about 150mm deep. ( different advise from different web pages.)Can anyone give me an idea of the quantities I need to order. Also the base will butt against my path should I use an expansion board when it joins ? will also have to drive over a manhole cover, is there any mark on it to show its strength, i.e. to hold a car ? Apologies for a second problem, but I hope to do both jobs at once. One of the problems I face is not knowing the correct name for parts etc,Water drains off my neighbours roof and ends up on my path, It has no where to go as it was laid level, so it regularly become a large puddle. I would like to put a "gully" ( probably wrong word) again the wall where the eater lays and run it to my drain. I would then want the fix a grill over the gully.I have seen this a number of times, but cant get any real guidance from the net as I seem to be searching the wrong words.
Any help greatly appreciated,
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