Hmmm I'm exploiting a loophole here and going a bit Back to the Future.
I'd go back to when I was 16. Save the money I was making in my part time jobs until my 18th and, with the forsight and knowledge of various sporting results, Xmas number ones, big brother, X factor, general election and referendum results, spend 24 years cleaning up the bookies arriving at 45 much more than £1m richer.
Not forgetting not to bump into Mrs LUC along the way mind.
I am absolutely not going back to being a 16 year old, so red it is.
I'll go back to 16. Seeing as I'm 20, it shouldn't be that hard... I could pursue my dreams from an earlier age. Lovely.
Red
Id definitely go back and put alot more effort into my life and avoid people who took advantage of me etc 
would be hard but it would be better in the end and the happiness id hope to have would be worth more then 1 million pounds
Go back, at my age i’d rather live my life with a little foreknowledge. Not that i’d change much, but i would insist certain loved ones changed their lifestyles so they’d still be here, or at least not die young.
Back to 16 it is ! As long as we can know what we know now . I could keep from breaking my back , along with avoid some other big mistakes . Imagine investing back when you were young because you know what investments would be good ones .
Also at my age five years in the future could be beyond the end game . No need to rush to the finish !
Being 16 was awful for me. Years of challenges, mental illness, abusive partners etc. I’ll take 5 years and the million. Oh yes.
If I get to keep the knowledge I have now, then I would press blue to be 16 again. I don’t think I would change much, but having the foresight to tweak and deal with things would be helpful.