Selling to downsize and buy a larger property again later is likely to be an expensive option due to the costs of buying and selling property, so probably to be avoided.
Do you have any scope to take in a lodger or do air bnb?
What's your current lifestyle/spending like and is there any scope to cut down so you can live on a lower income? Would you be willing to do this?
Eg if you're currently a £200 pw Waitrose shopper, latest iphones on £50 pm contracts, lots of eating out and bought lunches from nice places, beauty treatments, PCP car, lots of spending on nice home accessories, expensive holidays etc etc, a more frugal lifestyle could save hundreds, if not £1k+ pm by eating a more basic diet from a cheaper supermarket, only occasional eating out, little or no paid beauty treatments, cheaper holidays. Looking for deals on everything you buy or do.
Maybe have a look at your current position with the moneysavingexpert money makeover and see where you could possibly cut back.
www.moneysavingexpert.com/family/money-help/
As for what to do with any money released or saved up, obviously it needs to stay in cash or cash like products so you're stuck with instant access, so the interest earned will be small, but you can get a bit, eg the best rate is now about 0.6% or about 1% if you put some in a fixed rate, so £60 or £100 a year on £10k, or you could gamble this by putting it in premium bonds. So better than nothing and always worth having if you don't have much disposable income.