Spousal Visa

I have been with my partner for 6 years, I have found out she has overstayed her visa. She needs to return home so that she can be with her family. We will be getting married abroad and then fill in the spousal visa form. My questions as an overstayer voluntary returned
1. What is the best way to fill in the form, I meet all the requirements other than her overstaying
2. How long is she likely to be stopped from entering the UK after voluntary returning. Am I best filling in the form as soon as we are married
3. What evidence am I best producing for the immigration services

Any advice will be helpful

I have been with my partner for 6 years, I have found out she has overstayed her visa. She needs to return home so that she can be with her family. We will be getting married abroad and then fill in the spousal visa form. My questions as an overstayer voluntary returned
1. What is the best way to fill in the form, I meet all the requirements other than her overstaying
2. How long is she likely to be stopped from entering the UK after voluntary returning. Am I best filling in the form as soon as we are married
3. What evidence am I best producing for the immigration services

Any advice will be helpful