The Stags made a winning start to life in the semi-professional ranks, beating Gloucestershire All Golds 36-18 last week.
Mbu said: “They’ll be a decent outfit, they’ve got some London Broncos players, and I don’t think anyone should take them lightly.”
He added: “I was encouraged by our performance last week. We showed a lot of maturity and control.
“We could have easily started trying to overplay, but we stayed disciplined and executed things well. Hopefully it’s a sign of good things to come.”
Hemel stand-off Chris Stevenson faces a fitness test on a knee problem before Troy Perkins names his Stags squad.
However, James Howitt will definitely be unavailable for the next three weeks due to personal reasons.
Perkins said: “We’re under no illusions this week will give us a tougher test than last week. We’re playing against blokes with Super League experience, and others who’ve been in this league for a long time.
“Where we dominated physically last week, it might be more difficult for us on Sunday. We’ll have to aim up in the forwards if we’re to have a chance of winning the game.”