wet room to standard to bathroom

if it a council owned property i would contact them first as not sure you will be aloud if you just want a bath in place of shower in some cases you can just leave the floor and fit a bath ontop of it but that depends on few things best get a bathroom fitter out to see, any good one will give free advice and alot easier to do so when seeing the job

If you do remove the non slip floor you are best the cap the drain & latex the floor level before installing your new flooring or tiles

You will have to apply for permission to the council in writing for any improvements you want to do before you go ahead. Anything you do without permission may affect your tenancy, however any improvments at no cost to them may go in your favour. I would say to let the bathroom fitter to see the job , you may get the best advice

Ask the council, they may even do it for you. If your prefer they didn't, you could fit the bath straight over the top, or remove the floor if you prefer an alternative. Also depending on the shower waste they've used, you can run your bath into there with minor alterations. Worst part will be getting hot and cold feed to the bath taps.