The best advice I was given was to buy really good underlay. It makes all the difference to how comfy the carpet feels and all you then do later is replace the carpet but reuse the underlay.
I go to the carpet warehouses that have offcuts. You can get really nice, huge pieces at a fraction of the cost. It is also worth getting a carperfitter to work out how much you need. I ended up getting loads of nooks and crannies in our oddly shaped house carpeted as they came out of what would otherwise have been wastage.
The underlay she was trying to flog us was £7.99 a metre and it was made from recycled materials (clearly she realised I smelled of lentils and knew this would appeal). She said it was highly recommended by their fitters.
I'm looking at the moment too and have come to the conclusion that the choices in Allied /Carpetright etc are rubbish - I've been told though that the 80/20 mix is the best as it's easiest to clean.
I've also been looking at sourcing the carpet (found the make I want and have found it much cheaper via internet) and then will get a local carpet fitter to put it in - seems to be a few hundred quid cheaper this way if you can be bothered - You can get a quite good 80/20 mix (neutral berber type) in B & Q for £11.00 a metre which seemed pretty nice. I think you would normally pay about £15 a metre for a mix and nearer £20 a metre for wool. The one I want which was nearly £16.00 a metre in the local carpet shop I've sourced for £11.50 a metre....
Pea, on the underlay thing, the guy in the internet shop (which I wierdly found out was 5mins from my house - pure coincidence) showed me this 7mm underlay which is made from old recycled carpets - not the rubber Tredaire stuff - and it was about £2.75 plus VAT a metre. The guy who showed it to me said that, as a carpet fitter, he really loved to work with it - it's fire retardant etc etc but I really don't want to pay almost as much for underlay as for the carpet. Don't let them flog you the most expensive and ask them to show you diff types.
Best underlay is cloud 9 it feels very thick to walk on and doesn't fall apart like the usual rubber underlay.
Go for 80/20 wool mix carpet, never buy polyprop cheap as chips stuff, it is harder to clean and does stain despite what they say. The pile also flattens very easily.
Use independent shops none of this Carpet Right malarky.
My Dad was a textile consultant for many years, started off working in a carpet mill so knows his onions!
Best way to tell quality of a carpet is the "smile" where you fold the carpet to see how much of a gap you can see between the tuffs of wool ie how much of the backing shows through. This is especially important if you are laying it on stairs where it will be folded back on the edge of the step.
<there ends the lesson that my Dad drummed into me on my first carpet expedition>
i've got 80/20 but the company that put the carpets in were crap and used rubbish underlay despite my repeatedly bleating that i wanted a really good one.
new carpet company who are now doing rest of the house said that if you put really thick foamy underlay under a cheap carpet it will look better than thin underlay under a good carpet. AND they said that a lot of the modern good quality synthetics are better than wool in any case.
underlay underlay underlay, arriba arriba (i am having a glass of wine as i type)