Depends on the traffic, the terrain, how the ails are feeling
Today, I did 57 miles in 4h 09, moving time, about 7 hours in all To do 30 miles around London without stopping (much) would take me around 2h15 I guess. My moving average is around 13-14mph according to strava
Does it matter however? I've personally never tried to ride a 30 mile timed ride, I go as far as I fancy in the time I have usually
Last Monday I did my PB: 32 miles, 1hr 43 mins = 18.6mph. That was a good bit faster than I had ever done before.
I am 31, 6'2 82.5KG. Cycled for 1.5 years.
If you've been cycling for just 3 weeks, I'd say your progress is good!