Thanks for your question, it's obviously a very difficult situation.
If she is deported then she can only come back to the UK after getting married and then applying to the British Embassy for a spouses visa to allow her to come back to the UK for a period of two years before she is required to make a further application.
Whether she would be granted a spouses visa will be at the discretion of the Home Office and the reasons for deportation will count very heavily against her. It is probably that the HO will refuse her application initially and she will be forced to appeal. Without knowing the full details of the case and her reasons for deportation it is impossible to say whether she is likely to be sucessful but, suffice it to say, she us up against it from the start because of her deportation; even if she left early the reasons for the deportation will subsist and remain noted by the HO.
It will probably take at least two months (and probably quite a bit more) from the date of her application before a final decision is made on her visa, and she will actually have to get married first.
If this is useful please kindly click accept so that I may be rewarded for my time. It will be gratefully received and you will be free to ask follow up questions.
DISCLAIMER: Answers from Experts on JustAnswer are not substitutes for the advice of an attorney. JustAnswer is a public forum and questions and responses are not private or confidential or protected by the attorney-client privilege. The Expert above is not your attorney, and the response above is not legal advice. You should not read this response to propose specific action or address specific circumstances, but only to give you a sense of general principles of law that might affect the situation you describe. Application of these general principles to particular circumstances must be done by a lawyer who has spoken with you in confidence, learned all relevant information, and explored various options. Before acting on these general principles, you should hire a lawyer licensed to practice law in the jurisdiction to which your question pertains.
The responses above are from individual Experts, not JustAnswer. The site and services are provided “as is”. To view the verified credential of an Expert, click on the “Verified” symbol in the Expert’s profile. This site is not for emergency questions which should be directed immediately by telephone or in-person to qualified professionals. Please carefully read the Terms of Service (last updated February 8, 2012).