M25 A10 or A1055 for that is just insane from Harpenden. Why wouldn’t the shortest route from A (Harpenden) to B ( Liverpool Street Station) not be a straight line?
Exit Harpenden on the A1081, jump on the M25 at 22 jump off at at Bignalls Corner more of the A1081, A1000, A1 to Highbury Corner. Then Canonbury Road, New North Road, Old Street roundabout, City Road and your more or less where you needs to be.
Next pay cheque invest in a proper paper based mapping system
I have done/do Enfield to Holborn and A10, down to Turnpike Lane across to Manor House and up to Holloway Road, Highbury Corner and Angel is pretty good on the way in. A1055 is horrible in the morning but better in the evening although once into Harringey everyone is out to kill you with their shite driving skills