Praise be to Allah.
We congratulate you for what Allah has bestowed upon you of guidance and enabling you to adhere to the rulings, teachings morals and manners of Islam. We ask Allah, may He be glorified, to help you to always adhere to the commands of Allah, may He be glorified, and to divert from you the evil of the devils among mankind and the jinn.
With regard to marriage to this person or anyone else, it is not permissible without a guardian (wali), because having a guardian is one of the conditions of the marriage contract being valid, as has been explained previously in fatwa no. 99696.
The fact that you have been cut off from your father for a while is not an excuse for marrying without a guardian. This is in addition to the fact that your forsaking your father for this length of time is something that is haraam; in fact it is a major sin because of what it involves of disobedience towards him and severing of family ties. We have previously explained that severing ties with one’s father and not upholding ties with him is haraam, no matter what the father may have done of bad treatment or falling short. So how about if the reason for that has to do with the child? Please see fatwa no. 87802.
Our advice to you is to hasten to get back in touch with your father, treat him kindly, and apologise for your shortcomings and bad behaviour. Then you can tell him about this suitor, and if he wishes he may do the marriage contract himself, so long as he is still a Muslim, or if he wishes he can appoint a proxy to do the marriage contract. As for bypassing your father and appointing someone else as your guardian, whether he is the imam of the mosque or someone else, this is not permissible. In fact some of the scholars were of the view that if a woman’s marriage contract is done by a more distant guardian, such as her brother, when the closer guardian, such as her father, is still alive, the marriage contract is not valid. This has been explained previously in fatwa no. 135233
So it is more likely that the marriage contract done by a non-mahram when the guardian is still alive is not valid.
With regard to what this young man is asking for of seeing you and meeting you before marriage, in principle this is something that is prescribed. This has been explained previously in fatwa no. 2572
But for you to go and let him see you on your own, this is not permissible, especially if that results in being alone together, because being alone with a woman is prohibited, as we have previously explained in fatwa no. 94019
Similarly, it is not permissible for you to go and meet him accompanied by a non-Muslim, because your interacting with a non-mahram non-Muslim is also not permissible, as it opens the door to a great deal of temptation and corruption.
Our advice to you in this situation is to hasten, first of all, to get in touch with your father and tell him about this matter, and wait for his opinion. If he agrees with you meeting this young man, then that will be by your father’s arrangement and in his presence, or in his company.
If that is not possible, then he may appoint one of your mahrams to take charge of the matter and be your chaperone.
If that is not possible either, it is permissible for you to meet him in the company of some trustworthy Muslims, and we suggest that it should be the imam of the mosque, or one of those in charge of the Islamic centre in your neighbourhood, and the contact or meetings between you and this young man after that should be arranged through this imam or the people in charge of the Islamic centre, because direct contact with him is a means that may lead to evil or mischief.
If the matter works out and the time comes for the marriage contract, then you should proceed along the lines explained above: either your father should come and do the marriage contract himself, or your father should appoint someone else to do the marriage contract for you in his stead, whether that proxy is one of your relatives or someone else.
Finally, we should draw your attention to an important matter, which is that it is stipulated that this young man who has proposed marriage to you should be a Muslim and chaste, because it is not permissible for a Muslim woman to marry anyone but a chaste Muslim man, as we have explained previously in fatwas no. 85335 and 118098
More importantly, it is not permissible for her to marry a non-Muslim; this is haraam and is an invalid marriage, according to scholarly consensus.
And Allah knows best.