Advice on GDPR

I was unemployed for quite a while and received advice from the Job center but I've never heard of GDPR until today. I've only just went self employed, I am a sole trader and currently work from home, I do take Names and addresses of customers (for postage only) but not bank details or any other personal information. would these new rules be something I would need to read through and print off? or are the new rules for large companies? I don't seem to fit into any descriptions of your drop down link so I chose the last one :( I've looked at the GDPR requirements and they're so confusing I thought it best to ask a professional.