Do I need a bathroom supply company and/or a builder?

I will soon be moving into my new home. I intend to get two pieces of work done immediately on moving in. The first is a complete renovation of the main bathroom, including new sanitary ware, new tiles floor and ceiling and a new electric shower.
The second is to create an ensuite in the master bedroom. This will involve taking a corner off one of the other bedrooms and then installing a toilet, sink and shower and all of the tiling as per the other bathroom.
My problem is that I don't know where to start. I know a bathroom supply company would do job no. 1 but am I right in thinking that they could not do the second job without me first getting in a builder to create the space for the ensuite?
Or if I got a builder could they do everything if I chose all the sanitary ware and tiles with them? Would anyone recommend taking this route?
Any advice on how to proceed would be gratefully appreciated?

We did something similar when we bought our house.
A builder will do all of these and arrange the various tradespeople required for the jobs - plumbing, tiling, electrical etc
We got some quotations for the job from tradesmen.ie but in the end went with one my father recommended.
All we had to do was pick out the tiles and bathroom fittings we liked. Apart from the mess during construction all in all it was fine and the end result was great.

Thanks very much RiceCakes. I actually just put the details on Tradesmen.ie last night and have been emailed the details of 4 people who hopefully will ring me tonight. Fingers crossed it will all go ok!

Be very careful to check out references from anyone you are considering using.

Leo, they give a list of references from people who have used the services through the tradesmen.ie website, as well as those given by the individuals/companies for work which hasn't come through that website. I suppose I still need to request contact numbers for the former and maybe to see the work?

Good to know Elginelf, just make sure the references coming from the site are genuine. So make sure to at least get in touch with these people.
Leo