Plumbers help required please ?

I dont consider myself a plumber by any stretch of the imagination but i do enjoy a bit of diy every now and then , i think i can put my hand to most household diy tasks , so my question is , my girlfriend wants me to fit a bath/shower mixer tap , in place of existing bath taps , i think i'll be ok fitting them to the pipes ok , with ( i guess ) , compression fittings and olives , etc ... , but wanted to know , as i want them deck mounted , are the spacings of the mixer tap holes going to be a standard size (width) uk ? , any help would be appreciated , thanks in advance ...