"Olly's a fantastic player - I've watched him from afar for a long time," Davies told BBC Gloucestershire.
"There's no need to rush him back and we've got to be mindful that it's a very serious injury and we've got to rehab him properly, so that when he does comeback he's as fit as he can be.
"It's about six months before Olly can get back on the park so we needed that cover in place."
Morgan made 16 appearances for Gloucester last season before being injured against Worcester Warriors.
Without another specialist full-back in the squad, former head coach Bryan Redpath used centre Jonny May to cover for Morgan's absence.
But Davies now has two options in Thomas, 24, who joins from Newport and Cook, 28, who arrived from Cornish Pirates last week.
Davies believes Cook's kicking ability will be an asset to his new-look team next season.
"He's been consistently good for the Pirates. He's very accomplished and he's also an 80%-plus goal kicker," said the Welshman.
"When you look at last season when Gloucester lost eight games by three points or less, that says something about discipline and our ability to take the penalties that come our way. He can certainly add to that and add a lot of competition."
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