First of all I want to say, I really am trying to ID the different species myself and have a number of resources. But in the end it just comes down to experience and there is so much of that on here. But I am trying! So here goes. My thoughts were maybe a Juvenile Whitethroat, or Juv. Greenfinch?
It's a Chaffinch - you'd probably have got that easily if you could see the wings, from this angle the features are less distinct.
Note the bill shape, peaked crown, and subtle head pattern.
Thank you so much Roy for taking the trouble to ID and for giving me the pointers, it really is much appreciated.