IMHO, using a TT with an arm that does not allow VTA adjustment is not a fatal problem, just restrictive and a PITA to set up. The problem usually arrises out of the differnt thickness of LP's which you might play. If your original set up is calculated for 180gm LP's it won't sound as good when you play 200gm or stuff thinner than 180 gm. You can do some down and dirty adjustments by just selecting mats platter mats of different thicknesses to compensate for the difference in thickness of the LPs so that you can always have an 'in the ball park' setting. An arm with an easily adjustible VTA is preferable. The other possibility which would help would be selecting a cartridge with a stylus that wasn't a line-source type, more conical in shape, and not as in need of an absolutely perpendicular cantact with the record groove. Your dealer could be right but you'd sure what to hear/research what he proposed as a solution.
BTW, IMHO, unless you have a preference for a speaker/amp combo that is best described as tonally neutral and tending to sound lean and analytical, and many folks do seem to like this, I think you would be dissapointed in the short and long run. But, if its free it is not much of an effort to plug it in, let it warm up, and get a free education. That is how we all learn, I think. :-) Who knows maybe you'll love it, they are your ears, not mine, or your dealers.