I have two vets I've used, one is about 400 yards away so extremely handy(!) and the other is a 10 minute train ride away. Neither are "cavy savvy"; they're just general vets, though I've never felt any treatment was compromised because of this. The closest vets has a 24hr hospital and emergency service, whilst the other has a visiting small animal/exotic expert, and when Willow was having her abscess removal they booked the op on a day he was working.
@TheCavySlave I wouldn't worry too much about them being "cavy savvy", I think it's important to have a good ongoing relationship with a vet. Of course, it's a huge benefit if a specialist is accessible, but in an emergency being able to get to ANY vet promptly can be vital. Perhaps look into whether any nearby practices have 'visiting' exotic experts, for example mine works at three practices. Don't 'write-off' any vets, even if they're not guinea pig experts they may be the best place to direct you to someone who is