I think you will find that timberbits are just another source of blanks that are available in the UK. Doesn't just mean they are buying from David (timberbits) and selling them on for a profit.
Tried putting a link up but keeps crashing, search for "acrylic" and you will find a thread for an acrylic comparison. Worth a look if nothing else.
However you can get blanks from forum members, some sell their "homemade" blanks.
Alternatively cast your own..
I'm not sure if Merv is still selling blanks, UK penkits..was a good source at one time or another.