I Don't really want to take as long to do the course as you, I have a job where I can work my hours round flying. Would like to finish by Christmas this year or very early in the new year weather permitting.
Then you're living in the wrong part of the world and starting at the wrong time of the year. An instructor is not going to risk his licence and livelihood by sending you off cross country in marginal weather - it's going to have to be better than someone who's a licence holder.
It was suggested that I went to my GP for a basic one then upgrade to another higher (class 1/2?) medical later. Surely wouldn't it be more prudent to have the higher class medical first?
It would - don't mess around. In fact, go the whole way. Are you just going to stay at PPL or are you eventually hoping to get a Commercial licence? If the latter is the case then book the inital class one at CAA house Gatwick. That's one of the stumbling blocks to Commercial Careers - you might as well find out now rather than waste a fortune to discover you aren't eligible.
Have a read of the links contained
here . In addition you can find your nearest AME (Authorised Medical Examiner) who can issue a Class 2 medical through the site too.