As most people point out - unless you want the special effects you can generate on a computer - using a domestic DVD recorder is faster an more trouble free.
However, as you are getting as far as you are, you must have a capture card, cable and software already.
I found that software can make a difference. Ulead Visual Studio is good and you can get a free download 30 day trial.
Next you should make sure that you have the correct settings. (I think UK is PAL-G but check this out - I am in Germany).
Finally make sure your cable is good.
As you will have found out by now - Video editing on a PC takes a lot of resource.