Enough posters have slated your speed so I won't bother, over the years i have have been caught speeding several times, best bet is be repentant and accept what is coming, at the speed you have posted the fine alone is likely to mean you need to sell the Z, as such I have to agree with those that say sell it, it can only make you look more repentant. Also, it really needs to be insured and taxed to be able to allow test drives etc so if you end up with a ban your insurance is likely to be invalid and it will be much harder to actually sell also, if potential buyers know you are banned they will offer silly money.
Good luck with the court date and hopefully you get a sympathetic hearing.
Whatever the outcome learn from the experience