Is it possible to replace a bath without having to redo the tiling?

is possible but you would need to be very careful. You would need to break the silicone seal between the tiles and the bath, using a stanley knife of similar, and then ease the bath out very slowly. It's also possible there is a secondary seal put in before the tiles where placed so be careful when easing the bath out as this could pull away the plaster and/or tiles. Good luck!

You may be able to fit new bath to existing tiles, I have done many, fit bath too low then raise up to tiles.

Hi Andrew, If you have enough space to remove the bathtub, by sliding it straight and there is not any other appliance in the way, you can remove the old bathtub and then install the new one with not big issues. Usually the bathtub is coming first and then the tiling around however, you could have for example: a space between walls bigger that the bathtub or the the bathtub it's surrounded by walls. In the first case you can replace just the bathtub (because one side is free) but in the second case, (in my opinion) it could be necessary to remove a couple of tile lines if you have not enough space to sliding straight the new bathtub. I hope that help you! Kind Regards D.Javier Tinte Cervell Ltd.