But it doesn't really work like that @sausagetheorangecat
If you spend £XX on your house, that doesn't mean it is worth £XX more. You don't always get the monty back. The work you have done may be the sort of thing that doesn't add value (such as decor, beyond a basic scheme); or it may be that prices are dropping or static and the ££ you have spent will just keep it at what you paid.
Years ago I sold a house for what I had paid for it six years before. I had spent ££ on a new kitchen and bathroom and central heating. But prices, having risen, had dropped right back down. It was fine though – I didn't buy it to make a profit, and I did the work to make it nicer to live in.
A house is worth what someone is willing to pay. As others note, if bigger 3-beds and 4-beds are on sale for the same or less, this one is probably priced too high.