If you're just beginning and have a really tight budget then you're unlikely to get anything particularly quality brand new, so start looking secondhand. I hate to sound opportunistic but I actually have a cracking secondhand practice amp for sale on here (click on "Trace Elliot Boxer 65" in my signature) which, as it appears you're in my area you're welcome to try, but it will good for home practice, coffee shop gigs, etc.
That would leave you £220 for a bass, cables, etc. This package from Thomann would give you what you'd need to complete a very basic setup: https://www.thomann.de/gb/harley_benton_pb_20lh_sbk_bundle_set.htm
Your can buy clip-on tuners cheaply, and you can experiment with plectrums, strings, etc in due course.