Or anyone else who can help!

I moved house back in August and at that time put Christmas decorations, suit cases etc in the loft. Back then, there were no obvious issues and the loft had been recently insulated. I popped up last weekend to hide the kids Christmas presents and noticed the felt liner was wet. The timber truss is fine, but obviously I want to fix the problem before they become sodden.
I flattened the insulation near the eaves to allow better through flow and at noticed there was no vents in the soffit boards, which are recently renewed also. So yesterday, I bought some retro fit vents and have been fitting them this morning.

On to the boiler now! The flue penetrates the front wall around 100mm below the soffit board and in my opinion, all the exhaust is flowing straight up into the loft.

Is there a specific flue extension for this type of problem or shall I just buy a regular extension to allow the flue to exhaust further away from the soffit?