The landscapes within the Bohemian Forest are amazing and are cannot really be found in Britain: plains and medium sized green mountains topped with pine forests and hosting a large fauna and flora where you particularly notice the relative absence of human population, The region, which however is not a national park, is abundant with an incredible number of pedestrian hiking paths or mountain biking tracks which allow you to explore the region in depth and discover its hidden corners.
I spent a weekend there, renting one of the several chalets located in the middle of nowhere. However despite the beauty of the region I recommend that during a stay in the Czech Republic you rather go to the Sumavas National Park which is, in my opinion, wilder, bigger and filled with more picturesque landscapes.