Certainly you can appeal to a magistrates court if you disagree with the DVLA's decision. However in this case the DVLA have yet to make a decision so there is nothing to appeal against.

Although the consultant has said that he considers you fit to drive the decision rests with the DVLA. It's for that reason that your case has been referred to their medical advisers. The timescale you've been given is broadly the same as I was given when I went through this earlier in the year. That said the 4 months they quoted me turned out to be 3 weeks, so there is hope. As you've found out you can't talk to the medical advisers, only to the front line staff. However your consultant or your GP (if he has the full facts) can phone the medical advisers so that might be a course worth pursuing.