(Are you sure about the dates? The Bell Beaker culture is typically given as beginning around 2800BCE and being replaced in different areas after 1800BCE, and the Britons come along about a thousand years later than that. I do have a previous answer on early Iron Age clothing on continental Europe, if that's of interest.)

As with most prehistoric cultures, we have very little idea of what the clothing of either looked like in terms of construction because of the lack of extant garments and detailed representative artwork. Barring frozen finds like Otzi, the best we can do is look at the stone/metalwork that textiles have rotted around in graves. (We do have evidence of wraparound kilts from bog finds in Denmark in the early Bronze Age, around the very beginning of the Bell Beaker period; trousers might have appeared in Britain by the end of the period, but it's all very loose.)

We do know that the Bell Beaker cultures made use of buttons as fastenings, particularly V-perforated buttons - buttons made with two holes on the underside that meet through a V-shaped channel, without coming through to the top like the typical two- or four-hole shirt button - but they used them in different ways. For instance, on the continent, they're frequently found in female graves; in Scotland and probably elsewhere in Britain, they seem to have been associated with men, used to close shorter jackets. Bone buttons could be made anywhere, but other materials could be used as they were available, like amber and jet; these would be more prestigious, since they're rarer. Cloaks, on the other hand, could be held with a large pin, or fitted with stone eyelets at the neck and fastened with a leather thong threaded through them. There's also evidence of men wearing narrow belts which could be knotted around "pulley rings".

We know that linen was in use from imprints of clothing on clay found at some Spanish archaeological sites. Since warp-weighted looms were being used to weave, it's likely that wool was also worn - on that type of loom, the weaver works from the top down, which is more conducive to wool (which is "sticky" because of the fiber's tooth) than linen. Typically a plain tabby weave (one over, one under) was used, which is fairly unsophisticated but perfectly functional.

It's difficult to define "advanced clothing" - apart from extremely prehistoric uncured skins, pretty much all clothing requires some level of sophistication to make. A warp-weighted loom, formed from a wooden post-and-lintel with at least two crossbars for use as heddles and the warp threads hanging from the top beam, is essentially the simplest form of loom, but it still represents a lot of work and technical knowledge. The same typically goes for this bone/stoneworking like we see here with the buttons and rings. Construction might be fairly simple in order to make the best use of the fabric, but the sewing might still be done with a high degree of detail and sophistication.

Does this help? I'm sorry, but I found nothing about armor in this period outside of Greece and the Near East.

Maria Pilar Prieto Martínez, Laure Salanova. The Bell Beaker Transition in Europe: Mobility and local evolution during the 3rd millennium BC (2015)

A. P. Fitzgerald. The Amesbury Archer and the Boscombe Bowmen: Early Bell Beaker burials at Boscombe Down, Amesbury, Wiltshire, Great Britain (2013)

Encyclopedia of European Peoples (2006)

Scottish Archaeological Research Framework. Early Bronze Age use of jet and jet-like materials, 22nd century - c 1750 BC