I've received a postal order, but the last letter of my surname is missing on it, can I still cash it?
You'll only know if you try. I suspect if you play it cool, it won't matter. If they point it out, just say "Oh, look at that! They must have mistyped it".
I've never had an issue with this sort of thing. Depending on your bank you can probably just deposit it in an ATM. I've never heard of a computer that even tries to read the "pay to:" section, let alone one that could figure it out if it was wrong.