Making some money, how do I create an environment where I can make a minimum of £250 a week as a return

A thought popped into my head, after I was ruminating about hemorrhaging £798 in five days. Between 10:30am Friday and 12pm Tuesday we spent £792 on nothing in particular, rent, food, travel, stuff. Today I get just over £115 in cash from something my grandparents set up nearly 50 years ago. Back then £115 was a lot of cash to have on a weekly basis, the spending power is the equivalent of between £2000 to £5000 a week. They obviously were not given sound financial advice about pegging it to inflation. Currently, we looking at an annual equivalent rate of 2.5%…. hmmmm! So every £100 gives me £2.50 a year.

So I would like between £250 per week over the next 7 years. How much do I need to have to generate that? The annual sum is £13000 net. Based on savings that would be 300000 lump sum I think.

I need to do research.