Bees nest in the attic?????

there are many species of bee 250 in the UK.

It's a bumble bee's nest. I don't know how common it is for them to nest in attics; they seem to have got well and truly tangled up with the insulation, or was that the rodent? At this time of year, it'll almost certainly no longer be active, the worker bees will all have died off and the young queens will have flown away to find somewhere to hibernate until next Spring, when they'll start new nests elsewhere. It's very unlikely that they'll come back next year.

I'm pretty sure it was the honey from the nest which had seeped into the surrounding insulation. Have removed that section of insulation and replaced with new.

That's a releif!!!

There's more here

I do unfortunately get wasps. I think they move each year.

Yes, wasps don't reuse nests. They all die over winter except the queens.

Doesn't look like a honeybee type construction but suggests a bumblebees nest. Try googling the bumblebee conservation trust for information. High up locations such as a loft might suit a tree bumble colony (bombus hypnorum).