reddit is a really good resource for this - reddit.com/r/ukpersonalfinance. It is reddit though so it's full of cringe neckbeards who take things too seriously.
I wouldn't follow any advice from this thread as none of us are regulated financial planners, but I would massively suggest looking into stocks and shares ISAs. Obligatory Martin Lewis article here: https://www.moneysavingexpert.com/savings/stocks-shares-isas/
+ remember time in the market is key so ideally you'd put money in this that you'd lock away for 5-10 years, but you can cash out if you need to it just takes about a week or so. AND most importantly the value of your investment can go up as well as down !
I will use this opportunity to say PLEASE DO NOT USE MONEYBOX their fees are utterly obscene, I know its just a quid but it'll likely cannibalise any interest/growth you see for small-ish sums, and if you take it as a % of your actual holdings it's significantly higher than any other S&S ISA out there. They're relying on lack of education + being one of the first to market (years + years ago, pre-Monzo I was using them) with roundups.
I have mine with Charles Stanley, I really rate them as a platform, and this is a personal choice so I definitely recommend you researching it before committing! IMO their fees are relatively low, and their customer service is 10/10. That's just the account, though, like Barclays may be your current account but you're not investing in Barclays.
I have my own & a joint account with my husband, and between the two I always buy (btw the ones in caps I've C+Ped from my account details so you can just search those on Charles Stanley and find the details yourself)
Vanguard Lifestyle 80 = https://www.charles-stanley-direct.co.uk/ViewFund?Sedol=B4PQW15
LEGAL & GENERAL UT L&G GBL 100 INDEX TST I ACC = https://www.charles-stanley-direct.co.uk/ViewFund?Sedol=B0CNH05
Do your research around these and you'll see why, there are plenty of similar funds and it just boils down to what you think after researching!
I then mix up between ethical funds for my account, pls note these tend to be more volatile but as a result arguably higher returns, my current 2 are:
PRESCIENT GLOBAL FDS PLC
OSMOSIS MORE WORLD RES EFFICIENCY D NAV
When looking at these they're likely all down because of the markets' response to corona virus lol but that's an ideal time to buy if you can afford it.