you might want to consider an application like NetLimiter, which'd allow you both to limit UDP activity in Bitcoin and monitor how much bandwidth the client's consuming
is it ok to block bitcoin on UDP port and just leave the TCP accessible?
No, and that's why you'd want something which can limit bandwidth consumption on an application level like NetLimiter. BTC still has to fully communicate, you just don't want uploading blocks taking up all possible upload bandwidth of your connection.