I am being sent to court for travelling on the railway without

I am being sent to court for travelling on the railway without having previously paid the fare and with intent to avoid payment thereof.
I admit to not paying the fare but there are mitigating circumstances which have been explained to the company and I have offered to pay the fare and other fares if necessary. They have not answered any of my comments.
My partner (who works for the company) and their daughter (who has a nominee pass) went with me for a night out. I have a normal oytster card. I had all passes in my handbag when we returned home, the daughter left hers in the bag as she rarely uses it.
Without really thinking about it, I was using whatever card came out first from my hand bag when using the tube. I know this is silly but I never really thought about it, and did not give a thought to the fact that the card is not mine - I thought of it as an oyster card like mine... Obviously this was really stupid.
I was stopped and questioned at a busy station where the ticket inspector did not speak the best of English and everything took place in a crowded noisy ticket area. I was embarrassed and late for work so agreed not to check the notes of the 'interview' and just left. His statement in the pack is simply not true. I did have alternative travel methods with me - I showed it to him. I did explain that I used the card because it was the first to come out of the bag. The record they provide shows the use as inconsistent (Approx 5 days in 2 weeks).
I completely accept I should not have used the card. I just cannot believe that nobody has responded to my comments or offer to settle the usage of the card.
I work in the financial sector and a criminal record like this will affect my future. I have no criminal record, am 28 and am educated to Maths degree level. Is there anything I can do to attempt to settle this out of court or will I at least get a chance to explain all of this in court as I expect this is low level and with a guilty plea will it just be a routine raised eyebrow and fine? I am in a real emotional mess with this as it has taken so long to get this far - they keep writing to an old address despite me writing and informing them of a new address twice - the offence was in October.
Amy guidance you can give would be appreciated. I am thinking of talking to a solicitor but the cost looks to be prohibitive even though I have no idea of a fine or if it is recorded as a criminal record.