OS MAPS & SATNAV

I was thinking of going for a ipaq bluetooth tom tom bundle for the satnav. I also do a lot of off road cycling and would like to run the OS maps as well.
Question 1. is the bluetooth gps receiver self powered (batteries)?
Question 2. If it is self powered, will it work ok if i through the receiver in bag on my back?

any help or experiances would be appreciated.

thnx

[Charlie]

1) it has a built in lithium battery which powers the unit. it comes supplied with an AC charger.
2) GPS reception through a bag is not guaranteed as TomTom say it needs a clear view of the sky....it has a magnetised back so could be mount on the handle bars.