those licence-free (actually they're "Licence exempt") radios are "PMR446" specification, and are only putting out half a watt.
If you want more range, either go for CB radio (more expensive, 40 channels, no licence required anymore), or as you mentioned above, Mobile phones (remember to have a phone operator in the car who's not driving!); the other two alternatives are PBR (Private Business Radio), which you're unlikely to qualify for, or Amateur Radio, where there's a Technical & Regulations knowledge-test-based licence requirement.
Oh yeah - you CAN get out of range problems with mobile phones - it's called "passing outside the service area", but with Vodafone, I'll agree that's fairly unlikely - they've been around long enough to have good coverage for most of the country on voice, if not data, coverage.
Hope the above helps