I had my bathroom done a year ago.Bought bath,toilet,semi ped sink and mira shower online.
Bought the tiles ,flooring,heated towel rail and spotlighting myself and got someone in to rip out and
do the work,he was a bit disorganised but got job done in about 10 days.
The lot came in at 2 grand,there is a website you can go on and ask for quotes and get reviews of local tradesmen.
Yes they do make a mess but grin and bear it.