well, it's definitely heading in the right direction!
i’ve been using a mix of wholewheat, white and rye flours to feed my starter and used strong white flour for the bread itself in an attempt to lighten things up. the second loaf wasn’t much lighter than my first attempt but yesterday’s loaf, number three, was much improved. i made a wetter dough – it had to prove in a bowl as it didn’t hold its shape – and this has really helped.
the air bubbles didn't extend all the way through the loaf - the ends and edges were good though - and i think this might be because i only did two rises before the final prove (it should be four). i will try again next weekend with the full set of four and see what happens. i am also going to bump up the salt content as it still doesn't have much flavour. does anyone have any other tips for adding flavour?