The British Library are hosting a PDF download service for British doctorates. Quite a few are available for free, some are charged for, and a minority will charge for digitising costs; it depends on the University supplying it. Some universities (eg. Oxford) have not signed up to the service, and need to be contacted direct for supply.
However, this means that some 'classic' brick and tile doctorates are now very easily available, for example Betts' brick and tile in york up to the 18th century, and McWhirr's Roman brick and tile. These are already scanned in, and available for download straightaway. Others have yet to be scanned and it will take BL at least 30 days, if not more, to do it. But at least it's opening up access!
The service is available at: http://ethos.bl.uk/