Welcome
Which side of Chelmsford are you? NS, E or W? I'm in the South bit but ride pretty much all directions. There's a fair few who ride in the area in different clubs and groups. I tend to ride by myself much of the time but I do go out with Chelmsford CTC ride on a Sunday when I can fit it in, 09:15 prompt from the City Council office next to the bus station in town.
14 - 15mph is bout their average speed but depends on the distance and time constraints you might have, Sunday's ride can be anything from 50 to 70 miles, home about 16:30 ish depending on the ride and weather. They know all the best lanes, cafe and pubs and you get a good bit of local history and chat on the ride to
Here's one of the rides on Strava, I usually make up the miles to 100km so often its about a 58mile ride for example:
https://www.strava.com/activities/272404668
I don't think you need CTC membership for a couple or rides with them, but to be honest, its not bad deal given the wiggle discount, YHA discount if you use them and insurance.
Blog diary of the rides:
https://chelmsfordcityctc.wordpress.com/
Schedule of next rides:
http://www.essexcycling.co.uk/chelmsfordcity/
I usually google the cafe & lunch stops with "strava" added to the search to get an idea of the routes, but its usually about 20 ish miles, tea & cake, then 10 miles to lunch, then 15 or so to tea & cake and 10 miles or so home.
If you can do the distance, I can also recommend the Friday's night rides. Next one is Whitstable (starts at Hyde Park Corner) - bonus points is you can join the Friday's as a club for £2 per year and then get CTC membership for £14ish !
Another good bunch of people to ride with.
https://www.cyclechat.net/threads/17th-july-2015-night-ride-to-whitstable.176181/