In reply to Bobling:
There is some good advice here
https://www.ukclimbing.com/forums/biking/commuting_to_work-689617
From your post, you don't commute far and want cost effective stuff.
Hi viz vests are very cheap from work wear suppliers, so cheap they are often left lying around.
Most super markets stock cheap led flashers which are good strapped to your bag/clothing to add visibility.
Ebay Chinese retina burning headlamps are effective and cheap, fit 2 to provide redundancy.
I use retired winter climbing gloves for bad weather commuting, the gaffa tape repairs keep the wind out nicely.
Feet in poly bags inside your shoes will keep them warm in the worst weather.
And mudguards, the most effective piece of kit to keep you dry.