Hi Rob
I just got a top notch job done which cost €1200 in labour and took 10 full working days.
A lot of different angles and bits of walls, blind stud wall with ledge at 120cm along one wall which has a 30 degree angle in it etc, window, walk in shower, tiled batch enclosure etc... so a complex enough job.
3.7m2 mosaic 1" square in 30x30cm mats (shower floor, steps and ledges)
43.5m2 wall tiles in 30x60cm tiles
5.5m2 in 60x60cm marble tiles (they took a long time as about 2.5cm thick and weigh a ton... and needed to be wet-sawed... and there was a lot of sawing needed due to all the odd angles and shapes in the room.
The guy spent about a day and a half measuring and working out exactly height of tiles and centred on window and door etc and marked it all out on the walls (and there are 13 different wall surfaces due to angled walls, ledges, etc and then there is the bath enclosure with a 30cm by 35cm step along the full length of the bath)... and still when you walk in now it still all looks symmetrical.
I did get a quote at just over 1/2 that price... from someone who is a pro tiler too and came recommended... but who would not have spent as much time on the symmetry, or on getting all the walls squared and levelled etc. Spending the extra was absolutely worth it when you see how it turned out. In the end still wasn't dear for 10 full days work I thought for someone who's a real craftsman.
BTW... most of my walls were plastered brickwork (badly out of square and with a huge kick towards the floor)... but there were some stud falls, enclosures and ledges built in to the room with wood. Make sure you spent the extra and get the full 1" thick Marine ply which is resistant to water for longevity... and in areas where there will always be a lot of water like the shower, bath enclosure etc... get that marine ply and then treat it with a shower tanking kit to ensure all will be good even in years to come.
My floor is concrete with underfloor heating poured in, so no wood on the floor for me. A previous house I rented had a huge bathroom and they only used a single layer of 2cm normal ply... it was a disaster. Too much flex and even with flexi-bond adhesive the tiles came lose within 2-3 months every time it was tiled. In the 4 years I lived there the room was retiled and grouted 5x. Also the boards got wet in between and warped because was normal ply and not marine ply. By rights they should have used two layers cross laid of the marine ply to make it rigid enough.
Hope the above helps with ideas, things to look out for etc.