register on www.loadup.co.uk and put in what you require and you will get some qoutes, often you can get a realy good price if you've got a transport company running back to ireland empty.
last year i put the lights on for the stock pairs 24/7 and had a greatbreeding season, the oldbirds could feed and water at will and keep the youngsters topped up.
check under the nest bowls for red mite but doughbt thats your problem!
If the birds have bred before then most likely they have been disturbed or just a coincidence you've had 2 die in different nests.