This comparison site may be useful as it comes up with a risk score for different options. Bear in mind its not an exhaustive list of options though.
If you do decide to invest in peer-to-peer lending, of the options I’m familiar with I’d be inclined to suggest RateSetter rolling account (targets 2.8% AER), Landbay Tracker account (targets 3.1% AER), or Growth Street (targets 5.3% AER). I believe Ratesetter and Landbay have provision/reserve funds which buffer investors from borrower defaults and late payments (to a degree) and they don’t charge withdrawal fees on these particular accounts (they do on other accounts on their platform). Growth Street loans are only 30 days long so you are only ever 30 days away from guaranteed access to your funds (minus any borrower defaults/late payments, I assume).
One thing I forgot to mention in earlier posts was some, but not all, platforms/funds charge a fee for selling your loans and exiting early. Zopa is one example of this so don’t go with Zopa for only a 6 month time period, and look out for this when choosing a platform.
Several peer-to-peer platforms have have referral schemes where you can earn decent cashback for signing up an depositing some money. I’m not sure if you would be able to benefit from these as they usually require a 1 year minimum investment period to earn cashback. But if you would like a referral to a platform, feel free to PM me. I have accounts with several of them.