Query ref former employer and taking me to court

Firstly long time lurker first time poster.

So my questions are surrounding a former employer taking me to court (this bit I'm not too worried about). But in a nutshell, the company needed someone in the business to pass a certain exam so that the company could get accredited in specific way to undertake certain work. I signed a schedule of costs for the training and first exam attempt which I failed, later on I took another exam which was not signed for as the company needed me to hold it so they specifically said (not in writing) that they would cover it and not make me incur additional debt to the company. I failed this second exam and not long after received a better job offer elsewhere and left. Upon leaving I paid back the costs of the training and exam of which I signed for in the aforementioned schedule of costs, but since the company are taking me to court for the other attempt.

Now on this front I have my evidence, the previous schedule of costs and the fact there was no second and an email chain predating my sitting of either exam of the company asking the 'body' that they whish to be accredited by what they need to be accredited (one person holding this specific certification) and could they apply before I had passed it. Plus some other docs.

But my real question is since this happened (not been to court yet) the previous employer has been contacted for a reference for my new role and for some vetting. And they have declined to provide a reference or confirm the dates I worked there and only stated that they are taking me to court. Is this legal that they can? Could I add this into a defamation claim as far as I understand it until a court decides neither of us are at fault in this matter.

I know the best solution is to get a solicitor but I don't have the money for that until nearer the court date it 'self. So want to figure out where I stand a bit better.