It is important that voters do not let the opinion surveys published by the press put them off voting. The result in your local ward is more likely to be determined (quite rightly) by local issues than by national trends. Polling by newspapers always underestimates the support for Liberal Democrats, smaller parties and independents anyway. This may reflect the survey methods, but I suggest that it is also down to bias in the way that the questions that are asked and the results are presented. There is no UK national newspaper which is committed to Liberal Democracy and there is a distinct Labour bias to the major South Wales newspapers.
So don't be put off by the headlines. Where there is a contest, there are no foregone conclusions. Come out and vote!