I am starting out on the Air Transport Management MSc at City University, London.
www.city.ac.uk/sems
They have a very flexible part-time programme, it is well-delivered, grown-up and attracts students from all over the world. you can start at any time and take between 1 and 5 years to complete the programme (1 introductory module as an entrance exam; 8 further modules, some core some elective; and a dissertation). The modules are each 3 days of teaching with varying exams/assignments afterwards. The course shares some modules with their Air Safety Management MSc and Aircraft Maintenance Management MSc programmes so there is plenty of scope for tailoring your own degree course.
I know a few people who have graduated from the City programme recently and it is well-respected in industry.
Fees are £9000 currently, payable in 3 installments as you progress. I am getting part sponsorship from work.
I have really enjoyed getting back to school. Good luck.