Are you 100% sure its bees? Only that sounds more like wasps - their activity levels will be high currently, and it may indicate the presence of a wasps' nest in the loft, especially if they're coming and going. Bees only gather if they''re swarming... if it is bees, find a beekeeper who wants them. Bees are protected, so finding a keeper who will come and deal with them is sbout the only way forward.

If it turns out to be wasps they don't survive the winter so its not a permanent problem.

Oh! Wasps, a friend of mine decided to fill the hole where th wasps were entering his wall but that wasn't a good idea as they went after him chasing him up the road & stinging him quite a few times, so leave well alone.
I don't know about you but I visualised him running up the road & did have a bit of a chuckle LOL x

When you say gathering, do you mean all together in a clump or just flying round waiting to get into a hole? We had the small bumble bees flying round near out gutters much earlier in the year and I was told they were waiting for the female to emerge from hibernation. Now that won't be it at this time of year, but they could have a nest in there, we have had before and I know of someone who has one at the moment. They won't do any harm and they all need all the help they can get, so if possible just ignore them.

Lots of sympathy & fellow feeling to your poor friend who was chased by wasps - its amazing how they can unerringly tell skin from shirt...