You might be lucky, dafydd! I'm a terrible lightweight when it comes to nicotine, any blend with more than a hint can knock me for six. (Of course, it doesn't help that I smoke too quickly, but still...)
A wee nic hit is fairly nice - very relaxed, proper time to sleep. I can smoke a bowl and happily lay down on the sofa for the rest of the evening, in a little nicotine stained haze!
But, yeah, too much makes you feel terribly ill, dodgy stomach, spinning rooms, all sorts.