Seems like we've all had similar problems with this kit in that area! I got mine to almost match up, but the dihedral is slightly off on the starboard wing, compared to the port wing, Hopefully, it's not too noticeable. I was able to fill the gap at the wing root with just a very small bead of Superglue, topped off with the old varnish and talcum powder mix - much easier than trying to get any kind of putty in there.
Jan, my Model Shop stocks brass, steel, ally and copper tube. I think the smallest inner diameter is 0.5mm. (actually works out at 24mm in 1/48th, but close enough!) I should have checked when I picked up some paint today, as I want some for future use, but I forgot! Doh!
The 'phone number is 01625 511646 if you want to check with Iris what she's got. But note, she's closed on Wednesdays.