There are two Scotland based guinea pig focused rescues.
Thistle Cavies Rescue
http://thistlecavies.tripod.com/
- I would recommend you ask Wendi what pigs she has available since her web site isn't often up to date since she's very pressed for time. Wendi is an absolutely delightful, friendly woman who will support you throughout the adoption and for the entire life of the pig. If you want, you can tell her that Koda's owner referred you to her.
Sokel Guinea Pig Rescue
sokelguineapigrescue.com/
- this rescue has a network of people who represent them throughout Scotland. One of which is located in Glasgow (as am I) It's my understanding that they are preparing for an influx of baby guinea pigs soon. I have been e-mailing respresentitives from this rescue for the past few days; all are extremely friendly, reasonable (not antagonistic or threatening) and keen to answer any questions and offer help.
A breeder who sells lots of guinea pigs, at a high or small price, who appear too young to leave their mum (3 weeks for a boy, 4 weeks for a girl) is known as a Backyard Breeder. Backyard breeders (or BYB) often breed sows to the ground, raising the pups on food that is as poor a quality as they can. The animals are often cared for poorly, infested with mites and extremely skittish and wary of humans. They are in the "industry" of pet selling for the money, and poor or sick "stock" is often neglected, ignored or culled.
Sometimes girls may arrive pregnant or are bred back-to-back which often leads to the poor girls imminent death from exhaustion or because she's too young to have to cope with reproducing on her own.
BYBing is not something that you should support - and by buying animals from a non-reputable breeder (a pretty high percent of breeders throughout the UK are not reputable) even though you may believe you're helping THAT pig, you're enabling that breeder, validating what they are doing by helping them to profit from it and helping to clear stock to make room for the next batch of babies.
So... yeah. Hopefully by pointing you toward those two rescues (both of whom are often happy to meet you half-way to take a pig to you!) you'll be able to find a piggie, if you're still keen to adopt.