Yes, 14 is too young to have sex in the UK as it is below the age of consent, age 16.
Many of us wanted and were able to have sex before we could legally consent but that doesn't mean you are ready.
Instead you should wait until you legally can (this protects you, your partner and parent(s) or guardian(s) -
And then wait some more: i) if you are not in a longterm, stable and caring relationship with someone of a similar age as you, ii) are not certain in how to protect yourself and your partner from STIs or unwanted pregnancy, iii) feel any pressure to engage in sex be it from your potential partner or from what you think others expect from you, iv) are not sure it's what you want to do.