Captainmacuk,
Sorry to hear about your misfortune and I suspect that you will have learnt a costly lesson. You talk about the conviction being recorded for ten years and BoeingBoy has already provided you with some useful and accurate advice. To clarify, the basic principals are as follows:
1. The conviction will remain recorded with the police and with DVLC for life.
2. Subject to some specified occupations you will not have to disclose the conviction to a relevant employer once the rehabilitation period under the 74 Act has expired. [section 4(3)(a)]
3. The most likely sentence will be a fine. The rehabilitation period in respect of a fine is 5 years (two and half years if under 18 at the time of conviction) after which the conviction is spent.
4. There is a mandatory 12 month minimum disqualification from driving. If you receive a second drink drive conviction within 10 years (and this is where you may have got the figure from) you will be subject to a minimum period of disqualification of 3 years plus whatever other penalty the Court imposes. For this reason the conviction will remain as an endorsement on your driving licence for the relevant period.
5. If you fail to disclose a conviction to a prospective employer when asked and before the conviction has become spent you are committing a criminal offence in that you are attempting to, or if you get the job are, obtaining a pecuniary advantage by deception contrary to section 16(2)(c) of the Theft Act 1968. I have known people to be prosecuted for this and personally I would not take the risk at the start of your career - a conviction for dishonesty will be much worse than for D/D.
Best advice as already given by others would be to come clean with any prospective employer.
That will be 250 guineas please.