I think you should talk to a tax lawyer or perhaps directly to HMRC. The company will have paid the training costs as a business expense - it will appear as a legitimate business cost to them and therefore they wont have paid any tax on that money. Why should you repay it back out of taxed income? not sure that makes sense..
Even if you have to pay it out of taxed income I can't see why you wouldn't be able to get a tax credit for it. Ask HMRC.