Recent studies have found that it is harder than ever to find a job in the UK at present. This is purely because there are more people looking for work following on from the recession where many people find themselves out of a job. There is much more competition for each job advertised so you really do need to make yourself stand out from the crowd in order to land the vacancy.
When updating your CV make sure that you highlight the unique qualities you have and experience / qualifications for that particular position. Ideally you want to tweak your CV for each company you are sending it to as each job will require a different skill set and you need to make the reader aware of how you believe you suit the position.
When attending an interview, make sure you are punctual, well dressed and prepared. If you can do all of these things it will not only impress but will give you the confidence you need to succeed.