The decision to sell and upsize is dependent on how the market is moving. I have adapted this from a guide to house buying to explain the maths.
In a market where prices are falling or have fallen there is an advantage to trade up. When people sell, there is much focus on ‘what will I get for my house?’ It is an important question, but if you are planning to trade up to a more expensive property, is that actually the right question?
For instance, if you have a property ‘worth’ say £100,000 and prices have dropped by 10%, this is now ‘worth £90,000 but you wish to buy a property that had a value of £175,000, and this too has dropped 10%, so is now available at £157,500. The gap between the 2 properties is £67,500. Had the prices been more stable, the gap would have been £75,000, so the saving now is £7,500.
Equally, if prices are rising, again using 10%, we see the values being £110,000 and £192,500 respectively, a gap now of £82,500.
This example shows how using a ‘poor market’ can be a great opportunity. Sometimes focusing on ‘how much can I get?’ is not the right question, when it should be, what is the difference I have to pay?
Put quite simply for the OP, the cost of upsizing may have fallen and a 3 bed is now more affordable even taken account of the lost value on your current home. You need to do local research.
Speak to a local agent and run the figures for your options. Bear in mind the additional tax on a second home if you decide to rent.