Congrats @sparkles512 
how exciting!
To help answer a few Q's:
Yes, you'll need to let your GP/midwife know you're pregnant. How you do this varies from area to area though - in some areas you call your GP and in others you can get straight in contact with the midwife or use an online form. Probably easiest to call your GP if you're not sure though.
It doesn't necessarily need to be done straight away so you can wait a little while to call if you want, or you can call now and they will probably put you in the system.
Your first appointment will be your booking appointment with the midwife. It's normally at around 8-10 weeks and is essentially a paperwork exercise, filling in your notes with medical history etc.
The midwife will then sort out booking your scan and you'll get a letter with your 12 week scan date.
If you'd like a scan before then you can book a private 'reassurance scan.' This can be done either at a private clinic (the types of places who do 4D scans etc) or quite often you can book and pay to have a private scan at your local hospital, usually in the ultrasound department.
It's possible to have an early scan from 6 weeks, but generally advised to wait until at least 8 weeks. 6 weeks is sometimes too early to see things properly and can cause more worry than reassurance.