Electra do a range for T gauge, but I think Adam (the man behind the company!) was in a nasty accident so hasn't been working for a few weeks. That may be the reason for no response! In the past he has taken requests! For me personally, I'm not a fan of the all over vinyl decal as it looks a bit shiny and it's also quite thick so can look a bit messy in T (saying that, I have seen some fantastic examples that look great...I simply don't have the skill or patience!)
You can buy decal paper so you can make your own decals and just print them off. This could work for you as you have already painted your models and these would just stick over!http://modelshop.co.uk/Shop/Finishes/Transfers/Item/Decal-paper-inkjet-clear/ITM4557
I haven't personally used this product, but that's the sort of thing I'm talking about! I have shopped from those guys before, both online and in store and I can only recommend them! They also do some good scatter materials and trees as they supply products for architecture models which also happen to be in the 1:500 range.
Hope this helps!