Please Help - Girlfriend overstayer in UK - Spouse Visa

Hi,

Firstly, I am new to the forum so my apologies if I have posted this in the wrong place or have gone about it in the wrong way.

My girlfriend is 30 years old from Belarus. She entered the UK legally 8 years ago. However after 4 years her Visa expired but did not return to her own country.
For those of you unaware, Belarus is regarded as the last dictatorship in Europe hence why she decided to chance her luck by staying in the UK.

Whilst I wish on the one hand she hadn't overstayed, on the other if she hadn't we would never have met.

I am a UK citizen, full time employed in the UK and meet all of the current requirements in terms of finances & accommodation etc.

We got together a year ago and fell completely in love. She is an amazing girl & we want to spend the rest of our life together. We intend to marry early next year.

To cut a long story short, we want to Marry and spend the rest of our lives together in the UK legally. What are our options? And how do we go about this?

I can imagine there are a lot of post like this however as we all know they have changed the law & are now checking people leaving the country. Your thoughts and help would be so greatly appreciated. We are just a normal couple, deeply in love who want to be together that's all.

Thanks

John