May be a bit niche - but if you use my LINK to open an account with Wealthify, invest £250 for 3 months, you (& I) will both get £50 each added to our accounts.
You can then withdraw it (and your £250 too)
You can take some/all of the £250 out at any time, but you then won't qualify for the bonus.
Martin Lewis Money Savings Expert had a similar Wealthify offer in the summer - invest £75 to get £75 - but you had to keep it in the 12 months