Trace Elliot combo for £60 on Gumtree. Collection from Hampshire. Get it serviced for around £50.
https://www.gumtree.com/p/guitar-instrument/stage-bass-guitar-amplifier-integrated-with-speaker/1410108621
If you want to save £500 of your budget you should consider an Ashdown EVO 180. If you want to annoy the neighbours a bit more you could get a valve MAG300 for an extra £50 or so.
I have the EVO 180 in my living room - more than I would ever need and the reassurance that if it ever went wrong I could probably run it down to Sussex myself and get it repaired.
I would be remiss to not recommend a TE combo (as long as you do not plan to move it yourself).