The Welsh Cob, is covered by section D of the, Welsh Pony and Cob Society Stud book. Welsh Cob height 14hh to 15.1 (typically around 14.2hh) Welsh Pony, not over 13.2hh.
Of course you will slight variations, but Tomas123 is looking for something 16 to 17hh, so not a Welsh Cob. I like them very much, but they can be very strong, and zippy in some cases so I would not reccomend for a beginner, the ones I have had have also loved to jump and have quite a scoopy jump, so again not for a beginner.
I still say a Happy Hacker, not to strong or willfull. (if such a thing exists, my 22 year old TB ran off with me a few weeks ago "and" cleared a 4ft stone wall, with me hanging on for grim death lol)