So can you explain what you want? It's difficult for us to advise based on the information you've given.

ok
A graduated nd filter, the square one with a holder for landscapes that make the sky darker. Ive been told the nd8 ones are the ones which give dramatic pics. The trouble Im having is that there seems be loads of differnet ones with different types of holders, basically i need to know which holder to get and which filter ie p series,z series and so on as thats what im stuck on.
heres a link that shows a £50 z121s nd8 http://www.warehouseexpress.com/buy-...ilter/p1000836
but then theres this http://www.warehouseexpress.com/buy-...ilter/p1000667
which is a nd8 £17 p121f
and then a x121s for £56 http://www.warehouseexpress.com/buy-...ilter/p1000920
this is what im stuck on and the holder for whatever filter i get.
Thanks

For each of th e links you've supplied, click on the "specifications" tab, and it will tell you which size the filter is. Pick a holder that fits the filter. The ones you have pointed to are series Z, P and X respectively, as indicated by the part numbers.

Typing in the text "filter holder" into the warehouse express search box, gives these results.
http://www.warehouseexpress.com/sear...ilter%20holder
Pick a filter holder to suit.

Narrowing the results down a bit:
http://www.warehouseexpress.com/sear...er&brand=cokin

Hi again Joe, I think you will find the "P" size is best - I have several early "A" size but they are too small for todays lenses. The larger filters are intended for medium format or video cameras. Take you camera and largest filter size lens along to a shop and see how they fit. Get the holder and step down rings for your lens filter sizes. I tend to get Lee or Cokin branded filters as they are more consistent.

As a working photographer I only use the best tripods like Manfrotto and never settle for less, because my equipment is worth a lot of money and in order to protect my camera falling off I need a sturdy tripod. I'd recommend Manfrotto 190XPROB a sturdy and light weight aluminium tripod. It sets up in seconds with quick release legs for easy setup.

I'm very much an amauter with limited resources so my veiwpoint will be different than John's.
I've never had a camera fall off any of my ultra budget tripods - but they're not stable enough for any sort of challenging situation. (Wind, long lens, macro, long exposures...)
For general evening photography out & about they seem to work fine.
My second hand Manfrotto Triaut is rock steady, very easy to adjust (all the legs can be adjusted from the top) and has good height range (~2 foot? to over 8 foot without the head, or extending the column). However it weighs a ton, and even second hand cost nearly 10x the seven day shop one new.
It's great for studio work & digiscoping, but if I need to be portable forget it!

I've heard it said of tripods "sturdy, cheap, light - pick any two"
I suspect easy to use might be added to list, with out increasing the number of options you can pick :(

I think you'd have to see if you can find one of the increasingly rare photography shops and look at the range they have, as different people find different catches etc preferable. Have a good think about the other uses you might have for it before you commit as well -
How high/low do you need it to go?
How much weight might you put on it?
Do you prefer twist lock, or lever catches?
How hard will you be on it (frequent/professional use of occational/light)?
Do you want the ease of a ball head or the precision of a pan & tilt...?

All effect the right choice for you.

Its always worth remembering the tripod has to be able to take the weight of the camera and lens you use. When I moved from a Canon 350D to a Canon 7D (via the 40D) I found the Manfrotto kit I owned couldn't cope with the extra weight. The junior ball head on the 190xprob was not designed to take that weight
www.manfrotto.co.uk have a superb 'configerator' that lets you build a system around your needs. It shows you whether your choice of legs and head are balanced and the final outcome of what you want to use it for will give you the options to look for
Theres an old saying "You get what you pay for" and thats certainly true with Tripods - better to wait and get one that is suitable than buy a cheapo one that can't cope with the conditions you are asking of it.

Read this on the Cokin site http://www.cokin.co.uk/pages/main.htm As mentioned above you probably need the P sized filters.

Also see here, A grad ND8 may be too dark for normal looking landscape photos, http://www.cokin.co.uk/pages/grad1.htm

I have to agree, value for money you can't beat Cokin plus always lots on e bay. Phil.