Nice gesture by Mark.
If you have a method of cutting blanks yourself you could also visit some of your flooring suppliers locally as the showrooms usually have reasonably sized samples of hardwood flooring FOC if they think you're wanting to buy.
They are usually 18mm thick and look for full widths of anything from 100 - 200mm and a length of 120mm+ if you can. Smaller lengths are ok if you think you are able to turn crosscut blanks. most common are oak, maple, walnut, beech but there are others. You can get samples from companies on line as well.
Other sources of free or very cheap hardwood is old furniture from freecycle or gumtree and don't neglect the odd skip or two. Look also for thick cutting boards in the supermarkets or TK Max etc you can get a number of blanks out of a £5 board.