I have been with my wife to be for 8 years we have a child and all and we about to get married in less than 6 months the thing that worries me a lot is she doesn't want to have with me, she always morns and find excuses when it's time for sex, I don't know what to do any more, as it's making feel like I have to go and look for it some where else,

For two reasons I think you should postpone marriage: one is that she doesn't want sex and you do, and the other is that you haven't found out why. ASK her! Communication is key to any relationship.
Here's a few of the many most common reasons:
She feels trapped at home with housework and childcare and never gets out.
She feels unappreciated, unloved, unsexy, and treated like a mother and maid.
Your idea of sex includes no romance, no foreplay, much of which needs to happen throughout the days with little sweet acts and compliments, not just when you hop in bed.
You want sex at one time of day and she another (this has been studied and shown to be true, but I forget which men prefer and which women prefer).
She's tired, anemic, something medical, or she's depressed.
She's tired of being unmarried and is 'holding out' until she is.
ETC etc etc

Has she been like this for 8 years? How old is the child? How old are you both? Maybe its to soon after the birth of your child, or child birth has changed her libido. Hard to say without more info.

Hi thanks all for the answers my son is 4 years old and she is 26 and Iam 28 the thing is she wasn't like that before it all started when we had a misunderstanding when she was pregnant and she moved out and we had too many fights and all but we decided to make things work out and we did but our sex life is now if I don't ask for it she never does and it makes me wonder If it will change after we get married ?

Wondering will get you nowhere without asking.
We can't possibly know what she's thinking.
So ask her!

All she is saying is I am turned off sex because I always think of all the bad things you did to me in the past so Iam not feeling it, which means if you don't ask for it she won't even bother

all she is saying is iam turned off sex coz I always think of all the bad things you did to me in the past so Iam not feeling it, which means if u don't ask for it she won't even bother
You two did not resolve your issues before you got back together and marriage is not going to help things either.
Put off the marriage and do some couple counseling.

I would also be against being married at this time until the past is resolved. Doing the wifely duty is hardly an encouraging future. But I suspect if she is still holding on to old resentments your approach in other areas of your relationship could stand some changing.

Change is a process you may have to be guided through by a professional, since none of us here knows the whole story. There are ways if both partners are willing, the minds can be reconnected, and the bodies usually follow.

all she is saying is iam turned off sex coz I always think of all the bad things you did to me in the past so Iam not feeling it, which means if u don't ask for it she won't even bother

The issue is clear. Women can't turn off how they feel and just go with the moment like men can. For men, sex is sex. For women, it's an emotional connection. It's hard to connect with someone when you're mad at them.

You haven't resolved the past. Until you do, you won't get into her pants. Cheating on her will only make matters worse.

You both need professional help to resolve the past issues. Don't get into her head, and you'll never get into her bed.