You have 44 sq M - so to allow for waste say 50 sq M. With 6" boards there are 7 in a metre of width which means you will need 50x7 linear metres which is 350 linear metres. You should be able to source it from a decent timer merchant at around £1.50 to £1.80 per metre inc VAT. That works out at £525 to £630 with plenty of spare. Having a look around - http://www.builderdepot.co.uk/tongue-groove-flooring-22mm-x-150mm-sold-per-metre.html is £1.57 inc. And make sure you visit and see the quality before you order.
Builderdepot.co.uk 18mm t+g chipboard p5 £7.68 a sheet Inc vat, 44m you need 31 sheets, add 10% if needed for waste, 34 sheets, equals £261.12 if my dubious maths is correct.
I would never use chipboard, I was originally looking at 18mm plywood, TP do Redwood Tongue and Grooved Flooring Standard Flooring 20.5mm x 144mm at £920 +vat ( 350 linear metres) doing in ply 16 sheets £480
You should be able to get a good discount on those TP prices as a starter. Where in the country are you?
When fitting these is it one screw per joist per board or do you put two screws in a board on each joist? (floor boards)
I've seen peeps rip down 25mm ply to use as floorboards,& some using 15mm or 18mm sheets again ripped down & laid over a concrete floor, some finishes looked darn good.
44sqm is a lot of screws - prob not far off 2000. If you use a cordless and set the torque your wrist will know about it at the end as every screw puts a little twist on it. One of the best reasons to buy/hire a collated screw gun - they are depth adjusted not torque adjusted - no wrist strain. Also DO make sure you use flooring screws. These will have either a plain shank (no thread) under the head, or sometimes a short extra thread at a different pitch. If you use a fully threaded screw the boards will not pull down tight and will creak.
With around 310 to 320 linear metres to install, at 400 centres there will be around 6-7 screws per metre to allow for ends and joins which suggests 1860 to 2240 screws which ties in with your estimate Mr R. Only when you have used a collated screw gun do you really appreciate the benefits - time, speed, consistency, fatigue, blisters, sprains ... I can probably insert 100 collated screws in the time it takes to do 10 with a normal electric screwdriver - ad they will all be at 0.5 mm below the surface.
Mr R can provide a link to his good value budget one! Or the one I have is a Fein M-gun at around £250
I just had a look and there don't seem to be any left . When I got mine there were a load of discontinued Senco DS275AC (mains) on ebay at £80-90 . Old model >3 years out of date but works just fine. Only issue with this particular model is that the bits are an odd/unique size and you have to hunt them down. (I have a stock now that will see me good.) I wouldn't buy a cordless version of this model even if you find one - too old - the batteries won't be fresh. I'm pretty sure all the drivers will be suitable for floorboards. Mine takes from 35mm to 75mm screws - I've been using 35mm for PB and 55mm for boards best prices I can see are http://www.kelvinpowertools.com/senco-ds5525-auto-feed-screwdriver-c-36-p-8235 or http://www.powertoolworld.co.uk/mak...bNgt543kYrEoyamSvaIJ57id4Xdqw_TqDkaAkKY8P8HAQ
Potentially Timco for screws: http://www.timco.co.uk/screws/collated-screws/collated-flooring-screws Available from Orbital Fasteners https://www.orbitalfasteners.co.uk/en/categories/timco-universal-collated-screws Or possibly collated decking screws: http://www.screwfix.com/p/timbadeck-collated-decking-screws-4-5-x-65mm-1000-pack/2772p although at 65mm may be a little long! Which ever ones you go for, make sure your driver has the right tip - philips, pozi or square ...
+1 for Timco - perfect for the job. Do like the square No. 2 recessed head on them. https://www.tradefixdirect.com/scre...ver-bits-no2?gclid=COCR2p_54NQCFeq87QodrMkLOA