reliable UK online brokerage re slippage, software

Hi,

I'm going to start trading futures soon, mostly US but some European and Far Eastern.

I just need online order management facilities, no quotes or charting.

I'm not too fussed about the commission being higher than average, as long as the slippage is OK and the online order entry is reliable.

Does anyone have any advice, for instance Mann or Berkeley?

Thanks
Adam