Tilling or combe boiler, which first?

Need to remove the bath, prepare water pipe for the electric shower and tilling, the after fix the electric shower.

Always where possible tile first as this will give a cleaner look and more importantly give better sealant for longevity of your bathroom furnitures.

Shower and boiler go in first in my opinion

It would be more beneficial to tile everything first, gives the jobs a better finish as there wont be check outs around the shower, etc. Fitting the boiler however isnt usually tiled in, easier for pipe work to be fitted, boxing in would look better, as that can be tiled, or decorative mdf.

Its always easier to tile first but not necessarily important

In construction you have what's called 1st fix and 2nd fix. This means installing your bath/shower/basin/wc 1st, plumb it all in 1st. In your case and in every case, a shower mixer should be plumbed in 1st, an also the shower tray installed 1st. Then and only then start to tile. Tip: the first row of tiles on the shower tray, should be cut tiles, so then when I comes to the sling of the tray, you get a much better seal, protecting from any water leaks down the side of the shower tray. As for your boiler, it's hard to advise without seeing the placement of it. What you need to bear in mind is, when the boiler is installed, can you still tile around it? Most times though, at least have the pipework done 1st. eg, 1st fix. Get the pipes in the right place first, if the pipes are coming out of the wall. If your pipes aren't coming out of the wall, then simply tile before installing the boiler.