10k is enough that if anything goes wrong you have something to fall back on (Emergency fund) plus some funds for either a holiday or lifestyle change (flat, car). Keep a few grand in cash (6 months monthly spend) then the rest put into a saver until you have something you plan to buy and withdraw at that point only
Shares are long term investments meaning unless you plan to keep them there for 5-10 years or more, high interest savings accounts are a better bet. Though, recently, some current accounts have higher interest rates for the first year so keep an eye out and maybe just switch every year.