Some brokers offer it happypunter. I could see chi-x feeds at Amscot and IG but recently IG stopped showing chi-x in their depth citing problems with Reuters feed.
Amscot have also tackled algos (I think they had complaints from clients originally and brushed them away until their own house traders started complaining). I think they staggered orders to different venues so they arrive at the same time and cut out asx/chi-x arbitrage.
