
The two breeds you mention are very different, both in height, in temperment and in grooming requirement so it's probably a good idea to research both breeds thoroughly before deciding on what breed will suit your lifestyle. If you are looking for advice please contact the breed clubs, the contact information can be found at www.the-kennel-club.org.uk, click on Discover dogs, then breeds, then the breed you are interested in. Breeds clubs should be able to tell you of any planned litters and give you breeders contact details. Please be prepared to travel a good bit further from London to find the right dog and breeder. I do not know much about Parsons, but if you decide on an Irish, you may need to wait for upto and over a year (maybe two), so it is best to get on a breeders waiting list.
Good Luck :D