I have collected a few like this over the years, but from under eaves or in trees, not in a chimney apex like yours. It has to be said that this is a job which tends to need at least three hands, and I suspect that you only have two.
This looks to be about 25ft up. I would use a decent aluminium D rung ladder for this, but I am pretty confident on them. A helper standing on the bottom rungs is best to ensure stability when working. I find that you can normally borrow a suitable ladder in most areas if you ask around in advance. Wearing bee kit when enquiring is useful!
I would do a quick-n-dirty nest collection, and then sort things out after you have got it home. I use a bread knife to first loosen all side attachments, then go for a fast nest drop into a suitable ventilated cardboard box or whatever by slicing through the top of the combs, aiming to get the nest and as many bees as possible contained. You won't get them all. Either close up immediately or if there are MANY bees left outside, leave an entrance and hope that there is fanning to bring stragglers in.
The very best of luck with whatever you decide to do. If you are not confident, or can't locate the equipment you feel you need, be brave enough to walk away from this one. Your health and wellbeing have more value than a few thousand bees.