Wow, what a long opening sentence!
Your partner needs to be with you and your son at Christmas at least and, from there, a workable plan for your join futures discussed. You say you didn't agree to him living and working away from you for a while, despite him saying he was going to do it in order to improve prospects. It must be plain to him you have been virtually a one parent family to a little child for quite a while and that is unfair.
I can't help wondering if he was finding parenthood a bit much and wanted a break from it, despite him being the one who instigated it. That's not unusual for either parent but most acknowledge their responsibilities and grow up when they have a child. I do not judge you for not being so keen to bear the child, many people are talked into it (I know a youngish couple like yourselves where the woman was less keen than her partner but it worked out well in the end), however when their child arrives they love her or him regardless.
Lockdown would have made everything more difficult for all concerned. It has a lot to answer for (my son's engagement to the love of his life ended during lockdown because she was in another country and they didn't see each other for two years; she had a baby for someone else).
I'm very sorry partner's mother dislikes you but she too has to be more mature about the situation. You and her son have been 'an item' for a long time and you are the mother of her grandson, he should impress that upon her. Try to work out why there is this dislike.
What is partner like with you and your child when he comes home to you, is he loving and caring, sad to leave you behind or anxious to go back?
Do talk to him seriously and get a firm decision; meanwhile make a few plans of your own in case things don't pan out as you wish.
I really feel for you and hope you have supportive friends/family not too far away, are able to enjoy yourself sometimes and have enough cash. You don't say whether or not you have a job or where you are, it sounds like South Africa which is a vast country compared to here in England.
All I can do is wish you all the best, SimplyO. Please keep us up to date, everybody will be rooting for you and some others may have good suggestions.
Take care of yourself.