NHS salary sacrifice (tech benefit) do I have to pay back in full as I'm quitting job?

[doingitalllagain]

I've got £700 odd left and can't afford it in a lump sum but I'm leaving my health board. Will they let me pay in installments or do they require the full lump? Im anxious about it but I literally cannot stay

At our trust we take as much as we can back from your final salary payment and if there is a remaining outstanding balance it'll be invoiced to you with full payment expected within 30 days