[pcabc]

Market breadth can get complex and there are 500+ page books on the subject. SW's 'Weight of the Evidence' approach used over 50 indicators, but as you say, UK indices are thinner than US markets, however, that is where the UK stocks are traded and there is still value in plotting basic information like: highs/lows, advancers/decliners, % above/below MA etc. to get a feel for market internals, especially as this information is readily available and in may cases free. 

I'd like to have a go at maintaining my own index charts for say FTSE 100, 250, 350, AIM markets and as long as it doesn't turn into too much of a chore, would be a good accompaniment to SharePad.

If you could plot the relative strength of UK sector / industry charts against each other that could be quite informative but not rely on market breadth data.  Also, a good bit of advice I got from Isatrader was not to buy when market breadth was strongest, but when it was strengthening.  Buying only when it was stongest mean that I bought mainly at tops, a lot of my positions failed.