Invest in a house where river runs beneath. Real estate area you can't count full of gardens. No electric bill, water bill, maintenance fee. The architecture is nothing like this world has ever seen. If you have already done that by now
then
++++
Buy Land in BD. Preferably South BD. Since the Padma bridge is underway, the price will sky rocket in 5 years 3 folds minimum. More than anything in return you will get from investing in a restaurant/store in England. Plus you don't have to work for it, give time and energy. The only draw back is don't go too much south. Faridpur, Kushtia, Jessor, Upper part of Khulna.