carb,
How long did the sabbatical last, two years? I did a 3 year degree, a masters degree and a year out and I was 'free' by the age of 24.
I started applying for sponsorships rather late at the age of 23. Now that I am 26 I have a small list of things I can refer to when explaining that I am derermined to become a pilot:
A Class One medical, a few hours flying lessons, and about five almost successful pilot sponsorship applications behind me.
In comparison to others, my list of efforts to become a pilot is not very good at all, which is probably why I don't have a sponsorship.
To get a sponsorship you need to be able to prove that flying is your number one priority in life. Before family, before lifestyle, before financial freedom... Can you come up with a believable story as to why you spent so much time in university rather than working in an aviation related job?
It is very hard explaining these decisions. I've been trying for a while without success.
Good luck though!