I think I already posted a route for Billericay in your other thread? Cycle route 13 out as far as Stock, then, where it would differ from the other route, you can use lanes to come in the back of Chelmsford through Galleywood (Galleyend) then through Moulsham to the Cathedral.
Outbound, unless audax o'clock, as Bobb mentioned, I'd give the A road a miss and head via NCN1 which you could follow all the way to Ware if you fancied it, or short circuit a bit with some lanes along the way.