Has anyone retaken or taken GCSEs after leaving education.

I'm 30 and was looking to retake some GCSEs. I currently hold the following which I had taken in Aug 2008.

Maths C

English Language C English Literature D

Science(Double Award) However I only recieved a (C) maybe I did not so well on one

IT DiDA PASS

Initially my GCSEs hadn't held me back from future education as I went on to HNC/HND. However my future career prospects requirements are as follows:

You’ll need at least 5 GCSEs at grades A*-C (9-4) (or Scottish equivalent), which must include English and Mathematics.

What other subject can I look at taking a GCSE in?

How long did you have to study to retake for a GCSE? Was it a case of you joining the school attending that specific subject e.g. Science on Mondays/Wednesdays/Fridays 0900-1030.

Do GCSEs short courses still qualify as a GCSE?

How long did it take for you to complete?

I work a full time Job and wanted a way for me to work around this in order to complete the required GCSE as I can't bear the idea of going back to school for 2 years to complete a single course.

All thoughts and help is appreciated. TIA