Maybe I should stick w/ the .22LR
Your CZ 452 is a fine fine rifle, and there's quite a lot more you can do and learn with it in addition to 25yd standing. Try some 3-position and/or bench shooting. If you were interested in 200-300 yard target shooting with a .223, 100yd target shooting with your CZ would offer a good challenge as well. A nice happy medium might be to get a bolt .223 target rifle, and go to the range with both. Do most of your shooting with your CZ at 50-100yds, focusing on the basics (sight picture, trigger and breath control, etc), then shoot a bit with the .223 at longer range.
There are a lot of very experienced shooters who do a lot of rimfire shooting. Check out rimfirecentral.com for more info.