I think spare room has a 'premium' option where you can pay something like £25 to get priority access for a few months, otherwise you're limited to only messaging about rooms that have been up for a certain amount of time- there are some 'good deals' (they're still really expensive but not that bad compared to everything else) but they go really fast, so I'd recommend getting the priority access, setting up notifications like H.N. said, and just contacting about every room you could conceivably rent.