We have just done our bathroom and it's lovely (she says modestly).
My hints:
First, catch your plumber. Ask around for recommendations - good ones take a while (so get plumber and start date before you order a suite - or you will have it cluttering up your house for ages). Ours came and gave us a quote and a date to start and also recommended local plumbing suppliers which we found to be much better value and quality than big DIY places (we got the suite, shower and fittings for just over £300 - and they are much better quality than the ones we looked at in Focus, B&Q etc.)
The plumbing-in took a day - the rest dh did himself and it took months The bathroom looked awful but it was functional.
I wanted mosaic tiles but they were prohibitively expensive so in the end we went for white (cheap and classic). The advantage is that in future I can transform the look of the bathroom without too much hassle just by painting the walls and changing towels and accessories (aquamarine blue at the moment).
We ran out of money towards the end (well I had to have the Shaker style wall cabinet, matching mirror and a big stack of lovely aquamarine bath sheets from Lakeland!) so the floor looks like laminate but is actually vinyl. It came in strips like planks and could be cut with scissors so was a doddle to lay. Don't think it will last for ever but it will do for now, and it was so cheap (we got it at Wickes I think).
We also had a heated towel rail put in at the same time as the plumbing - warm towels, such luxury, but don't get a B&Q one (as we did) as the brackets that came with it were far too weak to hold it to the wall and it took a lot of faffing before it was sorted out.
The whole thing probably came in at around £800 which (compared to spacemonkey!) sounds ridiculously cheap but it is really nice, honest!