Thanks for your replies.
Just thought I should update with the outcome.
I went for the flow test with Uro Nurse and was told normal. Since then I have concentrated more on bladder training. I had previously been trying to hang on as long as possible and only go at what I thought was the last minute. With a lot of extra effort and concentration and at times literally holding myself I have now found that I can get passed that desperate urge until it eases or even disappears. Sometimes it can be another hour or so before I need to pee. This also gives me the confidence to go less often "just in case" when I know I won't be near a loo for a while. My capacity has improved and so has my confidence.
Hope this is useful for others with urge issues. It takes a lot of effort but you can improve.