Its just look messy. Are the windows okay? Does it need rewiring? Have you noticed any damp patches? How is the brickwork (could it need re-pointing)? Is the roof and guttering okay?
If its generally in good nick, an average new bathroom in London including installation is about 5k and an average new kitchen including appliances is 12k. Both can cost much more or much less depending on spec but that would be good middle of the road quality.
If you need to lay new flooring throughout budget 5k-10k depending on material (carpet / tile / wood) and spec.
If you hire someone to beautiful landscaping on the garden and replace the fencing etc that could be a few grand but if you can do it yourself it needn't be expensive.
If it were my house, I would add another bathroom on the 2nd floor. Houses with one bathroom and more than 3 bedrooms tend to sell for less as the ratio is unbalanced. Adding in a bathroom including the wastepipe connections will cost 5k potentially.
If it needs a new boiler and new rads that will be a 2-5k depending on spec (for a house that size you need a mega-flow and you might need to upgrade your mains pipe).
If the house is generally in good order, the 40k should do you before you add in anything special like installing a wood burning stove or getting a nicer front door or installing nicer lighting fixtures etc.
If the windows need replacing and you want to put in timber sash windows, budget 15k as a minimum- pvc will be cheaper but still expensive. If it needs rewiring, you will have to replaster and repaint the house so again budget at least 5k for the electrical work and plastering. If you are on a budget, paint it yourself as having house that size professionally painted is very expensive. If the roof needs work, that can be very expensive as well.
Good luck!