You should really try as many as possible, but I remember being a beginner and there was no way I was going to sit in a music shop sounding and looking like a complete noob, you might have more confidence however. Back then I bought a cheap Squier and in hindsight it was a mistake, hard to play, poor quality, undesirable image.
Moving to electric guitar a bit later I took a different approach, I bought the most desirable instrument I could afford, ironically it was a Squier Classic Vibe, goes to show how much the brand has changed. Owning a shiny new instrument of great quality made me want to pick it up whenever I saw it and encouraged me to learn.
My point is that you should get the best, most desirable bass you can afford, definitely don't spend less than £200. Buy second hand only if you are interested in saving money, owning a brand new instrument is a special feeling. If you have the money, spend it.
P Bass or Jazz are probably the best directions to go in when starting out as they can be functional as well as flash, Jazz basses have thinner necks so might feel more comfortable to begin with.
Find a P or J that you are comfortable playing, or if you don't want to expose your shortcomings in a music store then go with a brand with recognised quality control. Don't just buy a budget P bass copy. The Squier Classic Vibe series have an excellent reputation for QC and are often better put together than more expensive Fenders. A new Squier CV will leave you plenty of money to get a good lightweight amp and a looper to help you practice.