The 52 is a wonderful preamp. I had one for a short spell after having an 82 for a fair few years.
Your LP12 is very nice as it is and some prefer the pre Cirkus, valhalla style. What cartridge and phono stage are you using? You may want to start with a service and some dealer recommendations.
It’s a case of whether you want the modern Linn sound or the slightly fuzzy warmer sound of old which your CDS1 is more like.
Incidentally I have had 2 x CDS2s, very nice but ultimately unserviceable by Naim nowadays.
With the LP12 I would consider the following upgrades:
Tonearm: used Ekos 2 is very worthwwhile. I had one of these, now have Ekos SE. Your current tonearm, depending on condition should be pretty good.
Power Supply: Lingo 1, 2, 3 or 4 or Radikal (version 1 or 2). I have had a Lingo 1 which was very good. Now have the Klimax Radikal 2.
Bearing: Karousel. I also had Cirkus and pre Cirkus.
Chassis: Kore or Keel
You may get most benefit getting the bearing upgraded.
The order I did the upgrades was this:
Valhalla to Lingo 1.
Goldring carts
Tonearm Akito repaired, new bearings, rewired.
Kore and Cirkus
Dynavector cart 10x5
Karousel, Trampolin 2
Ekos 2 and Tom Evans The Groove MRX+ phonostage, Dynavector XX2MkII cart.
At this point my turntable sounded sublime.
Klimax Radikal, Ekos SE, Linn Kandid, Keel, Urika phonostage.
New top plate, platter and walnut fluted plinth.
So, I have done most upgrades to the LP12. The biggest upgrade was changing from Akito to Ekos 2 and Dynavector XX2MkII and Tom Evans phonostage. But I had already done quite a few by this stage.
If on a budget I would do the following: Service, Lingo 1 and Karousel and potentially better cart and phonostage.
Good luck!