for auto darkening there are 2 main manufacturers of "the unit" the cheap 20 quid one, and the more expensive 70 quid one, according to our local supplier
we use speed glas somthing like this
http://www.r-techwelding.co.uk/weld...Helmet_9100v?gclid=CLzd2u-p47cCFTMgtAod1A0Apg
edit
http://www.engweld.co.uk/product.php?prodId=760
we got em at around the 120 mark
I prefer fixed glass
at the moment i use
http://www.cromwell.co.uk/KEN8857160K
i advise not buying it the build quality is crap
was using a variable yesterday for a repetitive job to save the constant lifting of the mask
on the auto darkening their is a rumor going round the cheaper unit can cause eye damage, I doubt this and for light use i would just buy the cheaper units
obviously got cromwell
this looks like a decent local company
http://www.wilkinsonstar.com/wilkinsonstar/product_detail.php?C=WA&SC=WA-07&PC=BETA-R
don't buy their passive ones, they look cumbersome.
I look for the most minimal head unit possible what allows me the greatest range of movement, head room and not hitting my chest with the mask, the lack of sides on mine i also find handy.
but if your welding upside down i might get burnt
if your planning on tig i advise a variable especially the fact you will prob have scratch start
i got buy with my fixed for stick and tig, but i sometimes cheat n have a plate close to start on,
edit this is the one i was using yesterday,
SWP Autoshade Welding Helmet - Red: Amazon.co.uk: DIY & Tools, its the one we lend out when lending equitment, guy who said the rumor says this one has the better, unit