Our bathroom is a couple of metres square, and en-suite a bit smaller. In
each of them, I've used three of screwfix's (www.screwfix.com) MR16 IP44
rated low voltage bathroom downlights (3 finishes - part numbers 60962,
81219,37909) with 35W bulbs, and an extractor kit inc 35W light over the
shower in the corner, part number 25652.
I went for white and the white bezel on the shower extractor so it doesn't
draw your eye up to them particularly.
These downlights give a pretty good spread of light and having 4x 35W in
total gives you more than enough light. You can also get to the bulb very
easily to change it, as the bezel immediately around the lamp is a
push/click fit - no fiddly wire retaining clip.
I think IP44 is the minimum for zone 1 - which is effectively above the bath
in a normal house. You might find the higher rated IP65 units need the bulb
removing from above (i.e. the downlight needs prising out), and tend to have
a tighter light spread too.
I considered a lit mirror but I find them a bit too bulky. They always
remind me of those wall mounted light boxes you get in hospitals to view