Thank you for your question
How long have you lived together and are there any children involved?
Where did the funds come from?
How much is the house worth and what other assets are there
What income do you each have?
How much would a two bedroom property in the same school area cost to buy?
What mortgage capacity do you have?
Since the house was purchased in joint name you have a claim on it - but it will not be 50% nor anything close.
Even 20% could be optimistic - although not impossible, but there would be no need for a delay in payment - the court would see a mortgage as a reasonable option for her.
I hope that this is of assistance - please ask if you need further details