" i havent done this, ive practised mostly hands together, very slowly, as i found it was the coordination of both hands that was hard to achieve. i struggle to hear three melodies as i play, any advice? how did you learn to play the piece properly?"
See, in order to successfully coordinate this piece, each hand has got to fully know its part before all the pieces of the jigsaw can be put together. then you put the hands together slowly.
Regarding the voicing of fugues, this can be easily done by recognizing the fugue subject as it appears in its many forms, and bringing it out (though not as to completely overshadow the other voices), then everything else will fall into place naturally. This is how I learn fugues, and it really works.
What's my secret? Slow, hands separate practice before putting it together, and highlighting the fugue subject.
As for the pedal issue, I really don't know what to do. This piece heavily relies on pedal to sustain the intervals and also helps with the tone, which is probably a hard part of interpreting this piece. I only have medium sized hands myself, and pedal is definitely needed for me.
Here are some more tips:
at the end of the prelude, make sure the right hand is heard all the way through the rests in the left hand. use some pedal. it sounds AWESOME
also, remember that the mood of this fugue is sprightly. you don't want this piece to sound dead now do you?
Good luck. Getting this piece to come together makes you want to