Hi carp man,
Jollies is one of the best places to look, and there you can mix the seed you want to make the mix you want.
Many of the pigeon mixes are OK, but some need seeds taking out, as there is tomuch of one kind, and others need some seed putting in.
I grew up doing my fishing with seeds of all different kinds all year round, my Father used to Race pigeons, ( I dont mean he raced against them himself
). he also started his own company selling pigeon mixes.
One of the best as a basic mix will be called a Young Bird Mix, it doesnt matter about the brand, it's the finished seed that counts.
When you have got the mix you want, remember the most important thing to do is soak it for at least 24 hours, then cook it for around 20 minutes. If you dont sock the seeds long enough they dont cook as they should, and then they can cuase problems to the fish.
If you want to put hemp and tares in the mix, you wont find these with the bird seeds at Jollies, in my local shop they are with the groundbait.
Titmus are another company but not as cheap as Jollies