I don't think this is a good answer. It presumes the user learns all the channel numbers and the whole point of going to the guide to browse what's on. Going to a specific channel number is not what the original poster was asking about, and the mini guide is not large enough to be of much use, with just 3 channels.
Every other interactive TV guide I've ever used started from the channel being watched. Every. Single. One.
This is so basic I can't believe Virgin Media have ignored all the people who have asked for this for years. It appears to be an incredibly simple software fix. It's one of the reasons I stopped using the old TiVo for months, and even with my new V6, I find I'm only using it when I already know exactly what I am going to watch.