I think if you search the Army website for "insight course" signals and engineers have regular courses going, didn't ever see much for many other trades. I agree as well, you can't choose really where you're going to be based, or where you train, so don't do it to see what the army is like either
When I was at ITC Catterick the welsh lads had 7hour train journey's and didn't even bother to go home most weekends as a weekend on the train really isn't fun
Some Corps and Regts won't let you attend their insight course unless you are actually joining them. Your careers office should have details of a local course. After that, if you think the Army is for you, then try another. You can do as many as you want.
If you're still at school or college though, speak to your careers advisor.