Tom Jones . Get in contact with the embassy quickly then.. and have your fingers crossed that you will be allowed to enter.. Lots of restrictions at the moment here.
What visa do you have now.. ? Im guessing that you already have a 'B' visa because you had a work permit. ( Although it could be an 'O' visa) . If you have a 'B' visa and the name of your employer is written on it, then it's non transferable. So you'll have to get a new 'B' visa outside the country. If you have an 'o' visa , then your new employer just needs to give you supporting documents to help you obtain your work permit.
Looking at it at a different perspective.. And there's a few if's and buts too..
Apparently, family members can come here on the back of your long term visa ( if you have one) And if you were on an 'O' visa , then your mum would be on the same visa and therefore wouldn't need the medical insurance..
But I'm not sure exactly how it would work out. Maybe someone else knows. And then of course we got the new covid restrictions. So it's a long shot, but might be worth looking into anyway.