Welcome, Paul!
(yeah, like we really need yet another Paul here...)
I wouldn't worry about the .043, especially compared to a .045. Flats are quite a bit more massive, and it may actually feel heavier or thicker than what you are used to in a round.
Here in the states you would probably pay about $45 for a JF-344 set, plus shipping and maybe tax. I have been pleased to deal with
www.vintagebass.com, but there are others out there.
Not cheap, but if you do some further searching here, you'll find that some of us are happy to use them for years - they seem to last forever.
Just try a set and see what you think. Some people are immediately hooked for life, others... keep looking :-)
-Bob