Where Can I get data and information on currency vulme, for example I want to know the volume of the GBP/JPY before I open up a position.

As far as I know, there is no volume data available for OTC trading, because there is no central exchange for the forex market. Even the 2 Trillion dollars a day traded is only an estimate.

The one reliable source of forex volume is the futures market since that’s exchange driven. Just realize that it represents a relatively small fraction of the market.

I’ve made a killing with bloomberg service, cause they have reported the extremes with option volatilities. Everytime they report an extreme, I go long on the yen. Support’s been around 221.50 on GBP/JPY. I think Oanda’s news feed, 4castweb has option volatilities as a news feature as FXCM.
Enjoy the pip frenzy there. I’ll short below a daily low, since if there is negative momentum it will go right through, especially double zeros i.e. 224.00, 225.00 GBP/JPY.

Be wary of forex platforms that purport to offer a ‘volume’ indicator.

This is often just a pseudo volume measurement, which normally just consists of tick volume, i.e. the number of times that price changed in that time period.