Ok thanks to you all for your thoughts. Phoned up for my mac code today and will take the plunge with FTTC. Despite having not enjoyed my ADSL experience with BT, I'll give them another go....
I never could get greater than 7mbs on ADSL2/2+ on my line, then it went wonky and couldn't even hold a ADSL2/2+ connection. After lots of tests/engineers etc. the best solution was to go back to bog standard adsl. This did create a stable connection, but around 5/6 mbs depending on the time of day.
Last week I upgraded to fftc (40/2). I now get 36mbs down/1.8 mbs up - and so far, stable.
I am about 80 yards to the little GPO box and that is about 50 yards to the fibre box. I am about 1.75 miles to the exchange following the main roads.
if you have a high estimate eg. 60mbit, and if for some reason the line isnt stable on fast path, then downgrading to 40/10 would probably keep you on fast path due to the high snrm it would give you.