It is great that you have got into uni, congratulations.
I would weigh up the following:
Yourself - check out the town, the transport links, how easy it'd be to go back and see your mum and friends and family. Find out about local childcare options, affordibility and housing. Find out how intensive the timetable will be and how much childcare you will need. Do you currently rely heavily upon a local support network of friends and family, and if so do you think you'll feel okay about being a stranger (at least at first) in a new town and relying upon 'outside' childcare? Do you make friends easily and will you be happy to make a new network of friends?
Your dc - How do you think he would feel about about moving and do you think that he could adapt well considering his young age. At only aged 2 there is possibly less to uproot him from now than there will ever be as each year passes (ie once school starts and as he becomes more and more aware of his family and friends and literally of geography!).
Your mum -is she supportive of the general idea of you going to uni, even if not the moving part? It is clear from your post that she feels very close to you. I don't think leaving her should be taken lightly, but if you feel that this is your best chance for the career that you want then maybe you two can make it work. Can you go back and stay with her during half terms and holidays, can you meet up half way at weekends? It doesn't sound as though it's that far away.
Your ex - again, moving dc away from his father shouldn't be taken lightly but it doesn't sound as though it will effect ex's day-to-day life as he only sees ds every 2 weeks, as such would he, and most importantly dc, be able to adapt to the extra travel every 2 weeks? Where would he see ds?
Ultimately if you go you may find happiness there and stay forever, or you might end up graduating and going back to the town that you're in now. Either way you will have continued along the path to the career that you want.
If you decide not to go then don't give up on things, seek some advice about how you could go on to this career without attending this uni (could you apply to other unis next year? OU? or is there a vocational way to qualify or to work your way up.
Whether you choose to go or not, congratulations in getting in, it's not easy. 
