With almost absolute certainty, I am convinced that you do not need to practice with hands separately as your beginning piano student colleague will require.
For learning the Fantaisie Impromptus from Chopin, I forced myself to practise (AND memorize!!) the piece (beside the middle part) hands separated. My experience was that I learned and memorized it this way faster as if I did on comparable pieces hands together. The FI is maybe not the most demanding piece, but I would not call it a beginner piece.
Even now, if I like to perform this piece, I play it from memory hands separated and slowely. This gives me confidence, to be able to keep the track even if one hand would fail during a performance.
Maybe practising hands separated, has advantages even beyond beginner stadium. Just now, I am practising the g minor ballade from Chopin. The presto con fuoco part, I believe, get faster in the brain and faster in the fingers with hand separated practising. Just personal opinion.