BFP, what's the next step?

De
So I got my first positive in 2 years a few days ago, I have been testing every morning and the line is getting consistently darker. I'm from the UK so covered under the NHS. What's the next step? Do I wait a while then call my GP or do so straight away? This is my first baby so this part is all new to me. Can someone please give me some advice. I'm worrying about every little thing.