Don't use a big brand company. My decorator put in touch with a father and son team who do home improvements. They did my kitchen, shower room , new inter doors etc.
He told me where to get the tiles shower etc from it was a trade place he let me have his discount. I saved over £3,000. Also if you are having the bathroom made into a shower room for health reasons you can claim the VAT back on fittings not tiles or workman ship. It has to be fitted by tradesman to get it back I had £550 .
Ask around for recommendations from anyone local who has it done. Also make sure they do everything, plumbing,electrics,tiling etc.
My friend didn't do that and had to organise electrician,plumber ,plasterer and tiler herself. Cost a fortune.