Depends on how large we are talking.
Under £50k - I’d look at clearing off debt first and using any left towards either a nice holiday (been a while since we’ve had one), or start off a deposit towards a house if there was a decent amount
£50k-£100k - clear debt and put the remainder towards a house deposit
£100-£300k - as above, but much larger house deposit and some towards a holiday.
£300k-£500k - as above but probably outright buy a house, and maybe a new car & motorbike too
£500k+ - Same as previous, but any substantial extra would be invested to help with monthly costs.
Would probably put a smaller chunk aside for
bankroll too. The amount would depend on the win.