If you have a sensitive digital scale, try unwinding 10 measured yards of your yarn and weighing that amount.  From there, you should be able to figure at least an estimate of yardage in each 50 gram ball.

Not a purist at all - I tend to be practical and use whatever gives the best result for the task.  That said, I'd love to find a Singer Penguin Walking Foot.  The video makes it very clear how "walking" foot became the name.    

I have a white Featherweight and use one of these.  I'm in the US, but maybe the same type is available on your side of the pond?

The PUL I used is a laminated polyester knit, so it handled a bit like a thicker, slightly stiff knit.  With the thicker fleece, seams were... thick.  Also, pressing doesn't work.  The lamination can melt.  There are several types of PUL, apparently.  I was making a a washable dog mat, so I used the least expensive.  For your purposes, you may want to check into woven types also.  I've heard there is a cotton type, but cotton holds on to water, so possibly not the best for you.
Thinking more about this - your jacket might be heavy, since the PUL adds bulk.  It depends on your preferences.  I don't care for bulky clothes, so I tend to use the hi tech fabrics that are light and meant for things like jackets.  Have used the scraps to make dog coats as well, which means my dogs wear hi tech ski wear.  Neither they nor I ski... 

That's a great idea.  Once you know the alteration/s you need, it all gets easier.  Best of luck with it!

As I have narrow and square shoulders, I often need to adjust for that.  I have both woven and knit patterns in which the sleeve/shoulder fit perfectly.  I traced the armscye and shoulder areas of the F and B, and the top of the sleeve from those patterns onto a sturdy pattern material.  I simply lay/pin them over the relevant areas of a new pattern (making sure of the correct shoulder width and using the appropriate knit or woven one) and cut.  Works every time, even with weight fluctuations.  It saves all the slashing and shifting and taping on new patterns.  Patterns with intricate design elements in the upper sleeves are another issue, of course.

Not familiar with that model, so I can't help with which machine it fits. 


However, my experience with this type of cutter wasn't good.  It was by Bernina for my Bernina machine.  It created a huge linty mess all over the machine and table and the cutter seemed to dull and not cut as cleanly after a project or 2.  Have others had better experiences?