Look at a buy to let with 50% LTV – so £150k house/flat if you can find that. Need to look at exposure to interest rates vs rental income.
Aside from that the standard advice would be a diversified portfolio of investments. You probably need to get some IFA advice.
Some cash in a bank account – can be accessed quickly if needed
Some investments in the stock market – either just the UK or an international element say including Asia. These can be made via funds like ETFs
For £50-£75 I do not think you need to worry too much about tax sheltering like ISAs as the investment profits and hence tax liability will not be so great (even if you make 5% on £50k that’s £2,500 so probably no tax to pay). If gains on stock market investment start to exceed £10k (annual tax free amount) you can sell and repurchase them to cyrstalise the gain and mean no tax is payable.