Why do you need any clear space at all ? The 'trend' for the last 30 years has been to have basins that protrude slightly forward -- yes , I know , there's arguments for and against , but basically if you have oval basins , there is space to have liquid soap dispensers or whatever other accessories you want , even if your vanity was say 1200 x 300 -- theres no taps , so I actually think your vanity sounds a bit too big visually ( or the basins too small , although at 550 any bigger would be classed as a bath haha ! ) .

I’m not a professional painter but live in a old wood house with wood floors (inc bathroom), wooden windows and weatherboards so I’m comfortable with wood and water existing together. I don’t think you need your 4 steps. I would refinish the base including the legs (particularly the bottom of the legs)with a good clear wood sealer maybe something from the marine section - take advice from the paint shop as to which brand. I wouldn’t paint the top of that piece I don’t think the style lends itself to a two tone finish. I would use the wood sealer on the top as well and teamed with a white basin it will look quite smart. If you do paint the top any exterior paint would do the job, exterior paints hold up to rain and hail so should survive a bathroom. Make sure you seal well around the base of the basin. And check the finished height of your project. You don’t want it tools to use.

. Colours scheme looks great. I don’t think there are any rules, but eclectic mix might be good for that vintage thrown together look. It may depend on how the fittings turn out and what you decide for sink and bench top. My thought would be to steer away from shiny modern taps. Here are a couple of pics for inspiration, one looks like it has similar fittings on cabinet to yours.

Yes I have Polytec laminate in both my bathrooms, powder rooms and laundry. Our home is nearly 7 years old, and the laminate is still looking good. Most vanity’s have quartz or stone tops, have you asked the supplier to confirm your thoughts about being too heavy for the floating vanity? A photo of my children’s bathroom.