Can I fit semi pedestal sink if pipes rise up from floor. Will I need false wall to hide pipes. Bathroom fitter suggests I have vanity cabinet, but not keen.

What pipes? Water? Drainage? Both? No matter, Your pedestal lavatory (see image) is exposed and if you want a professional looking job you will have to open up the wall and bring the pipes out from there. Your only other option would be to install a vanity. Good luck
Tom