do u go to toilet before going to bed.....?

yes, it is necessery for everybody.

it's the last thing i do before going to bed and the first thing i do when i get up.

Of course... if I didn't, I wouldn't be able to sleep and would only have to get up to go after I had made myself all snug and warm. I think your natural insticts tell you when it's time to go, and if you bring the act forward by going before you settle in bed, then you get a longer time to rest before you need to go again. :-)