I thought I remembered someone who made some Type 41 (Cat Class) products. A quick google and…
Cammetts
When you go to their website, at the top there is a "Select a Category" dropdown list. Select the "Scale Caliber Model Ships Range". This will list a mix of Type 12 (Whitby / Leander class), Type 41 (Cats) and Type 61 (Cathedrals).
They do a Type 41 glassfibre hull in 1/96, loads of fittings, and also sell a 1/96 plan for a Type 41 both in pre and post modernisation forms – I’m sure one of them will be close to your Dad’s ship. Robin Cammett’s products are very high quality – I’ve seen them. Also I think he served on these ships so I think he would be pretty helpful if you drop him a line to talk about your project.
This should give you a flying start!
Pete.