British universities normally require UK students to have a minimum of 5 'high level' GCSE passes and at least three A-level passes. (There's actually a points system but it's probably not relevant here). GCSE examinations are taken at age 16 (after studying typically 9 or 10 subjects to that level) and A-level examinations are taken at age 18 (after studying just three, or possibly four, subjects).
A GED is equivalent to a US High School Graduation Diploma but (presumably due to the very general nature of the education involved) the body administering the university application process here (UCAS) regards that as only around our GCSE level. (See here:
https://www.ucas.com/sites/default/files/2015-international-qualifications.pdf ).
A university looking for students for its IT courses will almost certainly require, among other things, a reasonably good grade in A-level mathematics (or, of course, its international equivalent). That assumes (as far as our own education system is concerned) that candidates will have spent two years of post-16 study concentrating on mathematics as just one of three or four subjects which make up a full-time curriculum. See pages 11 to 27 here to see the typical course content for A-level mathematics:
https://www.cambridgeinternational.org/Images/203041-2017-2018-syllabus.pdf . If you've not got a qualification which proves you've got the mathematical confidences demanded by that syllabus it's unlikely that you'd be accepted for an IT course by a British university. (I used to teach A-level mathematics and it was generally only the very best students at that level who could gain a university place to study in the field of IT).
If you're still determined to try though, this might be of some help to you:
https://www.ucas.com/undergraduate/applying-university/international-and-eu-students/tips-international-applications