New SIM active no data and slow SMS

Hi I am a new customer and activated my SIM this afternoon it is showing active on the dashboard with a current plan, however the phone signal is alternating between 0 bars and all bars, and mobile data is either off or extremely slow on the speed test like 0.1 mbps. Although I can make a call the text is whirring for ages before it sends. 

Is it normal to have a few hiccups until things settle down. I was previously with Giffgaff and the signal and data were fine. I also was sure to check network coverage which was also fine for my postcode. 

It's only been active for about three hours so maybe it takes longer until everything's working normally??? Thanks. Adam