Anyone interested in trading in UK shares or etfs, derivatives and forex Have a look at the websites below
http://sites.google.com/site/ukstockbrokers/home

I trade with
www.svssecurities.com/

Its only £1 for first 30 days and only £5.75 after and don't even charge yearly admin fee

In volatile markets it might be good idea to trade in cfds, where you can buy or short shares but you can lose more than what you have invested. It may be good idea to put stop loss to limit losses.