Former Wales U21 guru Davey and ex-Celtic Warriors and Newport coach Lewis will lock horns as they bid for silverware with their respective men's first-team sides.
Davey, who is the Director of Rugby at the University of Wales Institute, believes it will be a hard-fought and entertaining cup final at England's HQ.
He said, "It's a great day out for all the players and everyone is looking forward to going to London for the match. The preparation has gone well and we are just itching now to get out and play after all the build up we have gone through.
"Hartpury are a strong side and have beaten us twice this season but we are quietly confident of winning."
The women's first team from UWIC will also face English opposition as they look to retain their crown against Loughborough University in the day's curtain raiser.
Davey added, "It has been a successful and prosperous year for UWIC on the rugby front with three of our teams reaching the BUSA finals.
"While we play at Twickenham our Freshers team will be playing up north against Leeds Metropolitan in the plate final so it would be nice to win the treble."