One thing here might be that the whole IT issue is rather woolly and it depends whose expert witness is more credible. Remember, they will supposedly be presenting to "Lay" persons and as such, it is maybe not going to be a case of whose witness is more knowledgeable, but whose is the better communicator.
If £3K rides on this, I would be prepared to spend just that to get the "right" expert. Should you win and I hope that you will - then money well spent. A nerd is of no use to anyone other than a nerd.
Be positive!(Then bite their balls off)
Conan