Hello Mr. White,
I assume you are looking for T Plate material FR4/G10. I also am assuming you are not in the US by the use of commas. In the US .047" (1.20mm) and .0625" (1.60mm) G10 is available through many distributors such as Professional Plastics or Port Plastics. Most of the material is made by Norplex or Atlas Fiber. There may be a few others but that is where my distributor mostly buys from. As far as custom sizes the orders you will need are rather large. I believe to get a small run of custom thickness you would be looking at 5-10 4' x 6' sheets (roughly 125 to 250 square feet at $4 - $5 a sq. ft.). Another thing to consider is that the standard tolerance on this material is +/- .0035". When you are asking for different sizes by .1mm (.004") you may not end up with exactly what you want. If you request 1.40mm you could get 1.30mm to 1.50mm and this would be within their tolerance.
Hope I could help a little.