This might be quite naive of me, but: In Canada, the way a bond works is a company takes out a loan from a bank in your name, and agrees to pay off the loan over a period of years until settled. If you leave before that period is over, they (your employer) just stop paying it for you.
Ergo, no legal wrasssling to deal with; you are just left "holding the bag", and it becomes a matter between you and said bank under the terms of the loan. So continue to pay it off in normal fashion, and you're in the clear in (this case) six months!
For interest's sake, can someone explain to me how the bonding issue is different in Europe/UK? In any case, good luck Monkeyball.