matt what you doing with th ceiling mate, it may be an idea to level it off, either with plasterbords or upvc/spotlights before starting on the suite,that way you'll end up with an even row of cuts around the top, if your ceiling isn't level you could end up with small cuts leading to big cuts which looks wank.
ceiling pic with an even row of cuts
ceiling first, first fix all pipework shower etc, fit bath and shower tray (if its resin bonded), then we tile the walls off a levelled off 2x1 timber batten which is normally 8" or so off the floor all the way round the room, do the walls and then remove the timber batten to do the floor, then put the bottom course of wall tiles in down to and on top of the floor, then 2nd fix whb,wc,shower, enclosure etc.this is a pic of a job first fixed and ready for tiles. this was a really cheap suite but the process is the same. bath done and usable, tray in and waste connected
i always use chrome plated pipe where it can be seen as well, its a much neater job when its finished,, even the radiator needs new pipework and chrome valves as they look shite without it. if you're doing a shorter towel rail do it something like this, as its a neater job, if its fitted at the same height as a radiator then the chances are you'll never use the bottom part of the rail, if its higher up (at least have the bottom of the rail at the height of the bath as a guide) you'll use all of it.

same one finished below
different job, same procedure
same one close up, really cheap b&q valves but a bit of chrome looks a lot better
even if you've got a tall towel rail the pipe work is better like this in the wall, it gives the room a tidier look than the pipework coming thru' the floor, nice clean lines
another chrome pipe pic
the walls and floor in this one were done before any of the units were fitted,
shower tray fitted as a first fix, then tiles, shower and enclosure fitted as a second fix after tiling, again nice clean lines around the room, mucho neatness lol
before
after, its all in the planning and prep mate.
i think i got those last ones the right way round lol