We have done three bathrooms now and I always buy everything separately and shop around.
Victoria Plum is the bad one, Victorian Plumbing are really good. They sell loads of different brands at hugely differing price points. So if you got something bad from them it’s the product/brand that’s bad not the company. They have a huge range so they’re worth a look.
Go to posh bathroom showrooms, they often change their displays and sell the previous display items very cheaply.
We used gerberit toilet frames - our fitter says he has never been back to fix a gerberit frame or flush, but says his heart sinks when people have bought the cheap versions as they always go wrong.
We got Duravit looks everywhere. Bought end of line ones/old styles off eBay or clearance sections of websites.
We have Grohe showers which are great, Hansgrohe are a different brand but also very good. We bought all bath and sink taps from Grohe too.
Tiling - we mostly used Tile Mountain who are fantastic. Saw them recommended on here. Very cheap but good quality, they will send you samples, great customer service.
Basically the things you want to spend money on are the things that have moving mechanisms - toilets, taps, showers. The things that don’t matter as much if they are cheap are shower trays (you don’t want a super cheap bendy one but composite ones can be ordered pretty cheap from eBay), shower glass - I checked with our fitter and he said the glass is the same everywhere. So decide what width you want 6/8/10mm and an 8mm piece of shower glass from eBay is going to be identical to an 8mm piece from a posh bathroom shop. Towel rails I didn’t splash out on either, just chose a cheapish one I liked.
We ordered bespoke sink units from a company I found on eBay called Harvey George. I found loads of units I liked on Pinterest and sent them pictures with our dimensions, and specified things like layout, sink type, granite top etc and they made it to spec. We have had two of those done and they’re both still perfect. However I recommended them to someone recently and noticed their prices have doubled since we used them.
For a small downstairs shower room I just ordered a fairly cheap sink unit off eBay that’s actually really nice and fit the space perfectly.