In reply to An Triubhas:
> For over the winter months is bouldering the best way of increasing strength?
>
Yes, up to quite a high level.
> What are people's thoughts on fingerboards?
>
Bouldering is probably more useful, but "supplementary" fingerboarding (for when you can't climb) will make you stronger. Injury is a big risk, so you just have to be very careful.
> What are the best websites / books for indoor training techniques?
Dave Macleod's website and book are great. The Beastmaker website is popular.