And maybe send a PM to Saskia. She and her husband Jonathan, who is from Puerto Plata, live in Herts. He went through the process a couple of years ago so it may help you to talk with a Dominican who has already done what you want to do.
The other thing you could consider is applying for a scholarship to study in UK
Scholarships and fellowships
http://www.chevening.com/home/index.html
The last group of Chevening Scholars here
Local press releases and news*Dominican Republic
Chevening awards are only for graduates, I understand, so you need to get your first degree first.
Best of luck to you! If you need the nuts & bolts visa stuff the links are below.
Brit Embassy SD visa info here
Services*Dominican Republic
Visas*Dominican Republic