When my repayments were due to start to HSBC (6 months after finishing Cabair), i wasn't in any position to pay the full amout as only had a job to get by while looking for an airline position.
I went into my local branch and they contacted the MK branch as this is where all the loans for Cabair are managed. They let me pay £250 for 6 months to get myself sorted. Luckily i got a job and managed to start paying the full amount after the 6 months.
Not sure where you would stand reducing the payments indefinately but short term maybe.
Best bet is to go to your nearest HSBC and sit down and have a chat with them.
Also i remember a condition of the loan / repayments that you had to be a permanent resident in the UK so not sure where they would stand if you went abroad.
Hope this helps
Rob