Dear lynnlingh,
You say that you are applying, which presumably means that you haven't yet gotten to the stage of being offered or even formally accepting a place on the Environmental Education course yet. When you do get to the decision-making stage, perhaps there are alternative attendance options on the programme which you could discuss with your academic adviser. Perhaps you could make up for less attendance by incorporating more study work at home and travelling less (a Masters degree is very independent in the UK, and I'm assuming the same is true in the US).
Also, you say that you cannot move because you want your son to continue living close to his dad - perhaps times when you need to attend contact tutoring are the very times when you could draw most on dad's support and ask him to look after your son then. I understand that you don't want to miss out on time with your son, but from a wider perspective, you could say that your son would in fact benefit more from having a happy fulfilled mum who is doing a course that she finds interesting and motivating - any time that you do end up spending with your son in that context will be even better in terms of quality. You could also find out if there are any grant-aided childcare opportunities through the University.
Also, losing out financially in the immediate term should really end up being compensated for in the longer term due to the fact that you will be more qualified when you finish the course, plus you are more likely to get a higher grade in a subject you enjoy.
Just a few thoughts, but I am sure there are many considerations you have to keep in mind, so good luck in your decision making!
best wishes
Ingrid