I am sorry to hear that your dealer is not displaying good customer service. I don't understand how he could not encourage you to try out any new machine you may potentially purchase! I don;t think the issue is you, since you are piecing no problem on your Featherweight. I think your dealer is just being an a** and that maybe you should find another dealer, even if you have to travel to visit one. (You have such a good rail system in the UK, even if you had to venture afield, it would be worth it in my opinion!)
I only learned to quilt 3 years ago, and at that time I had a $150 Brother from Wal-Mart. I kept having tension problems with it and become increasingly frustrated as I proceeded through the 4 month (once a week) night school class that I was taking. After taking it in for the 3rd time while still in the class, the dealer told me that I was putting good money after bad. That's when I decided to save for my Janome 4100QDC, and it made all the difference. I was able to justify the cost because I knew that I was hooked, and spending money on a good machine is important if quilting is something that you really love.