Thanks Simon - and for the offer. I have another guitar in the works and I'd like to make this a long term hobby. So I think it's probably sensible to buy some.

GluedtoMusic do the Hosoc straight ones individually. E.g.

https://www.gluedtomusic.com/product...ing-files-010/

I use 9-42 on all my guitars so I was initially planning to buy these gauges of file:

.010 .016 .024 .032 .042

I think I can use the .010 for both .009 and .011?

~£80 for five seems more palatable than the full set of ten (~£150).