John,
you might not do electronic banking, but I’ll bet your bank does, very happily.
You can safely share your name, sort code and account number via a pm as these data are on all your cheques anyway - and thus already in the public domain, at least those members of the public from whom you buy stuff! I’m sure this will be very much easier for you than being inundated with stamps.
I’m happy to do it as you've suggested, and I’d like a few tubes, but I do think you should name your price. And don’t forget the cost of cardboard, Jiffy bags, printing labels and sellotape!
A couple of other thoughts. There may be a Thunderer that lives near you, who might be willing to help, in getting the items to the post office, or of course, you might take it all to the bring‘n‘buy at a local model railway show.
best
Simon