As far as your plea goes, that is a matter for you. However, from your brief description of events it sounds as though you stand every chance of being convicted. The law states that you must adjust your driving when conditions are bad and it seems as if you did not do so.
As you have already pleaded not guilty you have now lost the opportunity to be given a full (33%) discount on any fine you may face. If you change your plea now (and I presume your next appearance will be what is known as a �pre-trial review�) you may still be given a discount, but reduced from the maximum.
You need to be fully aware of the consequences of the various sentencing options open to the court if you are convicted. Apart from the fine, you will either be disqualified or have penalty points endorsed on your licence (not both). If you are disqualified you may not drive at all for the period of the disqualification. However, when that period ends, you may resume driving as a full licence holder. If you are awarded six or more points, as a new driver (i.e. one who passed his first test less than two years ago) the DVLA will revoke your full licence. What Ethel has said is misleading. You will not be �banned� but may continue to drive as a provisional licence holder. This means back to �L� Plates and being accompanied, and you will have to pass your test (including theory) again.
Many new drivers ask the court to impose a short disqualification rather than points if they are likely to accumulate more than five. The courts sometimes accede to this request, but it is advisable to have a solicitor put this to the court on your behalf. If you are in England or Wales you will not get legal aid for this.