I assume you mean Pokemon Origins, as Googling 'Pokemom Trainer Red's Series' brings up nothing.
You can watch the episodes straight from Pokemon.com on their Pokemon TV provider. You will need to make an account with Pokemon.com to do so.
You can watch it on Amazon Prime Video using Amazon UK.
You can watch it on iTunes although this is quite a bit more expensive then the other options.
Pokemon TV is free. Amazon UK is about 4 pounds and iTunes is almost double that.
Hope I could help! Please let me know if I messed something up with regional purchasing.