u can take the newly completed D11 (E67), which goes to Hradec Kralove. It leads to Poland.
Czech highways are under development (D8 and D11 are being extended, D3 to Ceske Budejovice and Linz is supposed to be completed in 2020) so things will get better. Unless there are road works, there are only seldom traffic jams on Czech highways, with the exception of D1 near Prague (and near Mirosovice (direction to Ceske Budejovice and Linz, and Brno, too)).
Prague suffers from heavy traffic and on week days the main streets are one big traffic jam. Moreover, Prague doesn't have a complete highway outer ring yet. It is a really good idea to use the P+R (park and ride) parking places, where you can park your car for a very small fee and use public transport.
The P+Rs are situated near all highways and are well marked. Note that traffic wardens are rife and parking in most residential streets in and around Prague city centre (even after dark) without a valid permit will result in a parking fine. In particular, avoid blue-marked areas which are parking-restricted area if you don't want your car to get towed away within the hour
