Flatman underwent four Achilles tendon operations during his time out, which inevitably raised questions about whether or not he would return to top-flight rugby.
The 25-year-old won eight England caps between 2000 and 2002, the last of them in a stunning away win against Argentina, and Ashton hopes he can gradually recapture the form that made him genuine international class.
"It was fantastic to see him back against Sale," said Ashton.
"I am a massive David Flatman fan. I first worked with him in the England set-up back in 1999 or 2000.
"I think, with everything being equal, he is one of the best loosehead props in the country without a shadow of a doubt, and hopefully he will get back to the level he was playing at two or three seasons ago when he was breaking through into the senior international side.
"It will be a massive boost if he does, because it gives us a fair old strength in depth in terms of the front five."
Bath, just six points above Leeds despite their outstanding European Cup and Powergen Cup form this term, will encounter a Tykes side boosted by Justin Marshall's return from injury.
The former All Blacks scrum-half missed Leeds' 31-7 defeat at Gloucester last weekend because of a shoulder problem, but he is back to spearhead the Tykes' bid for a league double over Bath after a 16-12 away win in November.
Leicester can consolidate third place with victory over Madejski Stadium hosts London Irish, although the Tigers' poor away form - one league success on the road in 12 months - suggests they could struggle.
"It is a very surprising record, and it wasn't something I was actually aware of previously," said Leicester's Irish flanker Shane Jennings.
"It just hasn't worked out that well for us, but the players feel it as much as anyone. No-one wants to be involved in a losing team.
"During the season, we've played some good rugby, so it has been frustrating at times when we haven't come away with the results or made the scores we perhaps could have done."
England scrum-half Harry Ellis has made a rapid recovery from knee surgery and is among the Leicester replacements for potentially his first appearance since a hard-fought European Cup victory over the Ospreys seven days before Christmas, while Irish are without 10 injured senior players, including Justin Bishop, Riki Flutey, Darren Edwards and Nick Kennedy.
Leaders Sale Sharks will look to avenge a November defeat at Bristol when they protect a 10-month unbeaten record at Edgeley Park, and French star Thomas Castaignede returns to the Saracens line-up against Gloucester after recovering from an injury that ruled him out of holiday appointments with Irish and Leicester.
England flanker Andy Hazell, though, misses Gloucester's trip to Vicarage Road because of a head injury sustained during the victory over Leeds last time out.
Hazell is replaced by Peter Buxton, with Jake Boer moving to the openside, while experienced French prop Patrice Collazo replaces Nick Wood and lock Jonathan Pendlebury takes over from Adam Eustace.
And Wasps rugby director Ian McGeechan has made five changes in the pack as his team target a third successive bonus point league win following victories against Gloucester and Irish.
Prop Tim Payne and flanker Jonny O'Connor are rested for Newcastle's Causeway Stadium visit, while hooker Raphael Ibanez drops to the bench as Wasps field a front row of Alistair McKenzie, Jonny Barrett and Peter Bracken.
Lock Simon Shaw replaces John Hart, who moves to the back row instead of O'Connor, with Joe Worsley starting at openside flanker.