Issuing you with a warning, under Section 59 of the Police Reform Act, was simply a way of ensuring that immediate action could be taken if you continued to drive in the same manner. (i.e. it gave the police powers to seize to your vehicle if you were seen driving in the same way again, without having to wait for a court appearance). It's an entirely different matter to punishing you for the offence that you'd already committed.
Dangerous driving is a serious charge. If dealt with in a magistrates' court, the maximum penalty is a �5000 fine and 6 months imprisonment. If a case is referred to the Crown Court, the maximum penalty is an unlimited fine and 2 years imprisonment.
Admittedly, the chances of you being sent to prison are effectively nil and the fine will probably be much lower than the maximum (possibly around �400 + �60 costs + �15 victim compensation scheme payment) but your biggest concern will probably be the driving ban. Unless there are 'special circumstances' the court must impose a minimum 12 month's driving ban . The court must also order that you won't be permitted to drive again until you've passed an extended driving test.
'Special circumstances' almost certainly won't apply in your case. (For example, the potential loss of your job wouldn't count as 'special circumstances'). So it might be best to start studying the local bus times and saving to pay for your increased insurance premium (which will probably be at least 3 times the current level) when you've passed your extended driving test.
Chris