1. If you really like this girl Gary, I think the best way is for you to wait until she can finally get her ILR. Much easier.
2. If the marriage ends in divorce, prior to the individual being granted leave to remain, then the individual will either need to leave the UK, or make an application to remain in the UK in another category.
There can be various options available when making such applications in this situation, including the following 'grounds':
As a parent exercising rights of contact/access in relation to a child.
As a parent of a child at school.
As a victim of domestic violence.
As a migrant within Tier 1 of the Points Based System (Highly Skilled Migrant, Entrepreneur, Investor, post study worker etc.)
PS I copy paste No2 answer from this site
http://www.gross.co.uk/uk-immigratio...ls-divorce.asp
But on how to make these applications... You can check in UK border site