I've had fair experience in this department- if you know what I mean.
I too was booked a few years ago, 93 in a 60. Meant to get a detector, but waited until I was caught at 83 in a 60 a few months later!
Anyway, I got a Uniden SWS9800 or something like it. As its a radar detector, it falses quite a lot, but some like Bel Euro thing can switch off the Ka band. So far, I've had good warning of mobile radar traps, but not so good warnings of fixed Gatso sites. On these, the radar points away from the direction of travel, and unless there is a vehicle ahead which reflects the signal, the pre warning is virtually non existent.
However, it gives good warnings of Scamera vans, mobile radar guns, and laser or LIDAR tripid mounted traps.
The Road Angel, Geodessy, and Origin Blue all use the GPS system which can also be used to verify speedo inaccuracy! I'm not surprised by the results, but the 156 speedo is by no means the worst offender!
These GPS traps do not, unless like some of the most recent ones, give radar protection.
Furthermore, I don't know if they provide Talivan protecton. But I think someone ahead who has one, can log the site, but I'm not sure about that.
The positive side to this is that the investment which has kept my licence completely clean for over 4 years now, has more than paid for itself. My toy has cost less than my donations to HM government and the inevitable insurance increases would be!
Then again, I would be the first to admitt that good observation is still the cheapest defence!