SDS - Shop is fantastic, service I have had is second to none. Go to the shop, speak to Adam or Arthur the owner, try on lots of dry suits and undersuits, have a cup of tea... I spent a day there trying on kit, didn't spend a penny, looked eveywhere else then went back to SDS and bought the lot from there - they tend to be a few pounds dearer on a few items but it's worth it as far as i'm concerned...
They're mail order has been spot on too, i got my twin 7's/tekwing from SDS too and they didn't charge delivery as an extra... Can't recommend them highly enough. Last time I was there though it was quite busy, and difficult to get hold of someone, might be worth making an appointment or going in the week...!?
Consumables like torches/smb's with not too much to go wrong, I'd simply find the best on-line price (compare at
www.divebag.co.uk) and get from whoever is cheaper - bearing in mind that not every supplier is on divebag, but it's a good indicator...