Can I see Uranus and Neptune with a household telescope? Can I see Uranus and Neptune with an iOptron telescope with a 600mm focal length. If so, can I expect to see them in colour, or simply as white objects?
Yes, you can.

I use a Newtonian reflector, 200mm objective, 1000mm focal length.

Uranus is sometimes right on the fringe of naked eye but looks a lot clearer as a small but recognisable blueish disc.

Neptune, sadly, just looks like a star to me ... but you can find it.