Don't sell yourself short, man! You haven't made the noob mistake of not buying utility modules to support your oscillators.
I do think you'd benefit from a complex envelope/function/slew to really animate those wavetables. The typical suggestions are the excellent PEG and of course Maths.
However both represent a significant financial investment and are American. Don't forget you might find them used in Europe with a little luck. An alternative might be something like the A-171-2, which is easy on the wallet and HP count, and does lin/log. Nothing wrong with lots of Doepfer at all!
Here are some "fun" suggestions which I think could really expand your NW-1. Note they're not essentials and are US in origin:
Warps is a bunch of cool modulation algorithms for smashing either two separate signals, or a single signal with it's onboard utility OSC. It might be cool to mess with incoming audio and then dump it into the NW-1. Did I mention it has several vocoders....vocal wavetables? Warps can really open up some timbral options that filters can't quite do.
A joystick like the Planar or cheaper Choices are a TON of fun for wiggling wavetables, a method known as vector synthesis.
Hope that gives you some ideas! Check those used listings, you can have modular grid alert you when someone puts a module on the used market.