BFP- When to see GP?

So I got my BFP this morning, at 13DPO, which makes me 4 weeks pregnant (yay!). Since this is pregnancy number 1 for me, I'm not sure what the procedure is: When do I ring the doctor? What's he going to do? How does it all work?
Thank you for your help, ladies ❤️
PS: I live in the UK.