Adrian, I know exactly where you're coming from!
When I started karate, us beginners drilled & drilled the basics. Due to aikido class times, I've actually attended more of our dojo's advanced class than normal ones... Personally, my initial concern was that I was getting in the way, but every made me feel very welcome. I think I've come to the conclusion that it's all good experience, & to just stop worrying. I did feel pretty honoured one class, as it was just me & 5 black belts.