There was a woodturning weekend there last month and I took home quite a few blanks. Mostly common stuff. Sycamore, elm, ash, purple heart, spalted beech etc
Let your fingers do the walking. There are quite a few tree surgeons round our way who keep a stock for turners and furniture makers. You never know, there might be some in your area who do that too.
May I suggest that if you are wanting to purchase several blanks it will be cheaper to purchase a plank, the offcuts can be used for a multitude of other things and it will likely be cheaper than the equivalent prepared blanks?
If there is any one out my way with spare beer tokens you can always give me a ring, I have a very large create that I put all "blank" size offcuts into, there wont be anything exotic just run of the mill hardwoods but fine for learning and experimenting with. Before you ask I will not post these, I think you need to see and select what you are happy to use.
Not near West London. But there are local authority tree surgeons. Try contacting your local council parks department. They may be willing to let you have some logs. They will be wet wood and need seasoning but if you are learning then it is a good source of practice timber.
Well i live just outside south London and know of a couple round me were about in west london are you and i see if i can find one on another forum i am on
Our local authority chips all the small stuff and takes all the bigger stuff back to the yard. Then once a month they let the public in to take logs away FOC.