Phil
I think part of you is looking for some solidarity on here with your plight, after the best January in 4 years I have had the worst Feb and March (due to the weather), clocks changed and weather is getting better and a stream of enquiries start to appear (for me anyway).
If you have been going for five years and have managed to get by so far it would be a shame to jack it in now, besides I hear that despite the government telling us there are lots of jobs in the private sector, trying to find one that pays a decent living wage or does not have another 500 applicants along with you are few and far between.
For a bit of quick marketing have you tried bulk text messages, I use text tank (but there are loads on the web) much cheaper than royal mail and your pretty much assured that the customer has read your text as they cannot resist opening the message, Text every customer from last year with a special offer: Spring special offer, any 2 rooms £79, any 3 rooms £99, book before May 31st. I cant guarantee you will get any return but its another avenue.
Hope this helps
Tony