There will always be an element of luck to the game, the best thing to do is laugh it off. I know that might not be much good advice if you're losing all the time but there's not a lot else you can do.
What I will say is to get into a hobby or interest which relies 100% on skill and this can be your focus for serious study. Become an expert on a part of history or science which interests you or master chess or something. This can become your "main" hobby and playing WH could come second. It's more a psychological thing really, everyone likes to have something they consider themselves good at. If you choose something in which your proficiency relies 100% on your dedication then you will find that winning WH becomes less important because you have your "main" skill to fall back on when the dice don't go your way (if you see what I mean, it's kinda hard to explain)
The problem arises when people throw their heart and soul into a game and it becomes the be all and end all, they must be the best and master it. I was the same a few years ago, being a master WH player was very important to me and the fact that there were elements of the game which were beyond my control (dice rolls) used to annoy me quite a bit.
Once you see the fact that WH is nothing but a means for people with a similar interest to enjoy each others company then the focus changes and at the end of a game you can say "well, I lost, but did I enjoy it?" if the answer is yes then WH has done exactly what it's designed to do.
So combining all of the above I think you can cope. Of course I don't believe for a second you're a "bad roller", maybe use a cup if it makes you feel any better
