Unless you have space to move the doorway to the left so that the end of bath doesn't half-block it, in which case it can open inwards anyway, I think you'll come to regret the move.
Have you considered replacing the loo with one that has its cistern and pipework boxed in and forming a shelf below the level of the window sill for small items?
I don't mind pipework (it's a bathroom and, anyway, I like nicely done pipes). I'm not keen on things perched on window sills or the edge of baths, so I'd consider adding a shelf or two somewhere, perhaps in the corner above the bath.
If you have kids, it won't matter how many shelves and cupboards you provide, you'll still need more. :-(
EDIT: P.S. The pipes to the existing basin are probably 15mm and if so will need increasing to 22mm if you want to use them to fill a bath. The cold tap to a basin in a bathroom needs to be supplied with mains water, i.e. not from a storage tank in the roof.