I see you live in England, which means you have to become a Gold member (30 GBP a year) if you want to make a request online. I have been a Gold member for some years, but unfortunately didn't have any luck with ongoing searches so far. I have made many requests for almost every country in Europe, even requested Malta, Canaries. However we cannot travel any time of the year, requested certain weeks in February, April, October, July/August and we need 2B units. Also I like to plan far ahead so I can buy cheap flight tickets.
In my opinion DAE only works if you can be very flexible in destination, unit size and traveltime and/or if you can plan less than 6 months ahead.
Best is not to deposit first and just check the online availabilty frequently. This way you can see if it works for you without, like me, running the risk of not being able to use your credits.
Loes.