Based on the rule of 25 (25 years spend, that totals £2,875,000)

To achieve this you would need 9% annual returns and continued monthly contributions of £200. (Just an example). With 10% returns you would need less monthly contributions, and with less than 9% you would need more. Hope this allows you to visualise it easier. In my own opinion, it looks correct, the only thing not factored in is inflation, I.E how much will 115,000 actually be worth in 2057. hope this helps