As for the UK, property could give you decent return in relatively short time. Aim for cheaper houses (< GBP 100k, affordable for first time buyers), preferably repossessed by bank, located within less than 1 hour drive from the town centre of any major city. Don't do any major work on it, just refresh the look, give it a proper cleaning and re-paint.
If you're lucky, you can pocket out 30-50% profit in few months. If you struggle to sell, you can always try to rent it out.
As for Bitcoin. Definitely too risky to invest large % of your wealth in it. But as someone said on this forum: you have to be clinically retarded not to own some, just in case.
If investing in real estate, I wouldn't necessary go for houses because you have to do all of the renovations and it's difficult to keep that up while profiting. But good advice aiming for cheaper houses. Starting out with apartments in general may be better because you don't have to usually renovate the actual building itself.