I'd have a look for Bass Amps on Gumtree and see whats local, most 15-30w Bass Practice Combos will prolly have headphone socket, £25 touch... nothing really to loose, Google what ya find, or post here whats listed local to you... Fender Rumble or Squier from starter sets often appear.
Fuss free headphone only, this may be worth a look https://www.ehx.com/products/headphone-amp
Where ya based? someone on here may have something to try...