Thanks Moose, that’s sort of where I was leaning. The smart trainer idea was popping up because so many of my mates rave about it and not changing the wheel over all the time.
Pedals will probably be much more beneficial. Might even get a new Garmin head unit as well
Single sided or dual?
You have one of the best dumb trainers on the market. Personally, I prefer a wheel-off trainer, so I have a (dumb) Elite Volano, and TrainerRoad works perfectly. Replacing it with a cheap smart trainer might be a step down in some respects.
If you don’t have the money to upgrade now, then save it for something else. Save it for a TR subscription. Save it for a rainy day. Save it for your next bike. Or save it for a power meter if you don’t have one.
Without wanting to appear disloyal you can always use RGT for free, their real roads are very good. For years I used TrainerRoad with a KK Road machine and it was perfectly acceptable, I didn’t see a need for a smart trainer in any way whatsoever. I now do have one though, purely because I had some unexpected cash and there was a bargain to be had at the time, I spent less than £400 on my Elite Zumo and I have to say I really do enjoy riding it. Longer easier sessions are more easily achieved in erg mode as I can tune out from the target power and watch something else on the screen.
So, although you say you cannot afford TR right now if you did get a smart trainer you can use it elsewhere for free.
I know you didn’t ask me but if you were to go for pedal PM seriously consider the Favero Assioma Unos. If you’ve ever seen what @dcrainmaker and @GPLama think of them you wint be disappointed. I love mine.
Or the Assioma Duos if you can afford the bit extra. Then you can get into the game of chasing 50/50 leg balance (amongst other more useful benefits of having both legs measured). 
I had decided to go with the pedals until yesterday. I had a ride on the KK and noticed that my wheels was touching the ground quite a lot. After a close inspection I saw that the plate that has the arms on it for the wheel has hairline cracks in it.
As I bought it second hand it has no warranty (which is fine). This meant that I pulled the trigger on the Elite Drivo 2.
Thanks for all the advice. Can’t wait to get it
I originally upgraded from kk to a kickr snap before I did the pm route. Now I have a pm and a Saris H3. If I were to do it again I would get the smart trainer first.
For me I only look at the pm data after my outdoor ride and not during. Don’t get me wrong a pm is great to use indoors and out but I spend about 65%+ of my time indoors riding and the fun I have had with erg on TR and sim mode on Zwift was only enhanced with a smart trainer. A pm will not get you erg or virtual hills like a smart trainer.
Now if I had the $$ originally I would have got a direct drive before the wheel on but wheel on worked great also.