Hey Simon,
+1 for starting out with what you have... give it a crack, see how it goes & whether or not it meets your expectations... or not...
I've added some pics taken very early in my astrophotography adventure: Lunar & planetary taken through a Meade LX90 8" using a ZWO ASI224MC and M42 Great Orion Nebula which, from memory was using an f6.3 reducer & a Canon 1100d at prime focus (1.25" nose piece)...
Edit: Looking at some of the other posts, you'll see you can do way better than my early Orion attempt but, I was pretty happy at the time...
The image of Lagoon Nebula was taken a couple of years ago after I got my first EQ mount, a 2nd hand Celestron CG5 Adv. GT coupled with a Meade 80mm Triplet, also 2nd hand. I include this only so that you can compare early DSO AZ/Alt & SCT Vs early DSO with 80mm triplet & EQ mount....
Are they any good... well, I thought so & to be honest, I'm still pretty happy with the lunar & Jupiter shots... the DSO... well, as you can see from the Lagoon image, I've moved on through a couple of different mounts & scopes & whilst I still dabble... visual is my main thing...
Anyways, give it a crack with what you have.... you never know what you can do til you have a go...