Something like this?
http://www.screwfix.com/p/full-bore-lever-ball-valve-15mm/80413
What about connections?
I'm thinking about putting my pump onto this for recirculation and sparging and using the tap already fitted for draining the wort.
I've just received this today and it's a complete kit to replace the original tap on the Burco Cygnet 30l which I'll be fitting this week sometime between nightshifts.
http://www.ebay.co.uk/itm/1-2-Barb-Pipe-Stainless-Steel-Weldless-Compact-Kettle-Ball-Valve-Homebrew/262802827483?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649