[Zoggite]

Hi Geordie & welcome!
I wouldn't want to curb your enthusiasm but... I think you would be biting off more than you can chew if you were to launch yourself into being a locum straight out of uni, a bit like wanting to be a cabdriver when you've only just passed your driving test...
There is SOOO much more to the job (of community pharmacist, anyhow)than what they teach you at uni or even in you pre-reg time;learn the ropes working for somebody else, then launch yourself as a locum after a year or two.
The vast majority of locums I know are self-employed, which means that when they're on holiday, they're not getting a penny, but they can choose to work 6 days/week for a few months and then have a couple of months off or any work pattern they want.
"Is it easy to find work?" Answer: if you're any good, you'll be booked months in advance and be able to pick and choose where you want to go. If you're useless/lazy/sloppy/unreliable, bookings will quickly dry up.
Agencies: not indispensable,depends how good you are at "networking" and who you know; you could get yourself on the lists of a large multiple, they'll quickly fill you diary. A good reputation quickly spreads!
As for the mortgage question I really have no idea. Sorry!
Any further questions, just ask!